diff --git a/README b/README
index 07903da95..5a305d6ab 100644
--- a/README
+++ b/README
@@ -2,7 +2,7 @@
                      ===================================
 
                   © 1987-2005 Vrije Universiteit, Amsterdam
-                                2022-06-18
+                                2022-08-19
 
 
 INTRODUCTION
@@ -38,6 +38,7 @@ cpm           produces i80 CP/M .COM files
 rpi           produces Raspberry Pi GPU binaries
 pdpv7         produces PDP/11 V7 Unix binaries
 msdos86       produces i86 MS-DOS .COM files
+msdos386      produces i386 MS-DOS 32-bit DPMI .EXE files
 
 
 
diff --git a/build.lua b/build.lua
index 319571d8a..b0c2beebd 100644
--- a/build.lua
+++ b/build.lua
@@ -12,6 +12,7 @@ vars.plats = {
 	"linuxppc",
 	"linuxmips",
 	"msdos86",
+	"msdos386",
 	"osx386",
 	"osxppc",
 	"pc86",
diff --git a/mach/i386/as/mach3.c b/mach/i386/as/mach3.c
index 37f03566b..d5156ae0c 100644
--- a/mach/i386/as/mach3.c
+++ b/mach/i386/as/mach3.c
@@ -184,10 +184,13 @@
 {0,	NOOP_1,		0155,		"ins"},
 {0,	NOOP_1,		0252,		"stosb"},
 {0,	NOOP_1,		0253,		"stos"},
+{0,	NOOP_1,		0253,		"stosw"},
 {0,	NOOP_1,		0254,		"lodsb"},
 {0,	NOOP_1,		0255,		"lods"},
+{0,	NOOP_1,		0255,		"lodsw"},
 {0,	NOOP_1,		0256,		"scasb"},
 {0,	NOOP_1,		0257,		"scas"},
+{0,	NOOP_1,		0257,		"scasw"},
 {0,	NOOP_1,		0311,		"leave"},
 {0,	NOOP_1,		0316,		"into"},
 {0,	NOOP_1,		0317,		"iret"},
diff --git a/mach/i386/as/mach5.c b/mach/i386/as/mach5.c
index 4c07402fb..8815828ec 100644
--- a/mach/i386/as/mach5.c
+++ b/mach/i386/as/mach5.c
@@ -10,8 +10,8 @@
 
 void ea_1_16(int param)
 {
-	reg_1 &= 0377;
-        if ((reg_1 & 070) || (param & ~070)) {
+        reg_1 &= 0377;
+        if (param & ~070) {
                 serror("bad operand");
         }
         emit1(reg_1 | param);
@@ -39,542 +39,545 @@ void ea_1_16(int param)
 }
 
 void ea_1(int param) {
-	if (! address_long) {
-		ea_1_16(param);
-		return;
-	}
-	if (is_expr(reg_1)) {
-		serror("bad operand");
-		return;
-	}
-	if (is_reg(reg_1)) {
-		emit1(0300 | param | (reg_1&07));
-		return;
-	}
-	if (rm_1 == 04) {
-		/* sib field use here */
-		emit1(mod_1 << 6 | param | 04);
-		emit1(sib_1 | reg_1);
-	}
-	else emit1(mod_1<<6 | param | (reg_1&07));
-	if ((mod_1 == 0 && reg_1 == 5) || mod_1 == 2) {
-		/* ??? should this be protected by a call to "small" ??? */
+        if (! address_long) {
+                ea_1_16(param);
+                return;
+        }
+        if (is_expr(reg_1)) {
+                serror("bad operand");
+                return;
+        }
+        if (is_reg(reg_1)) {
+                emit1(0300 | param | (reg_1&07));
+                return;
+        }
+        if (rm_1 == 04) {
+                /* sib field use here */
+                emit1(mod_1 << 6 | param | 04);
+                emit1(sib_1 | reg_1);
+        }
+        else emit1(mod_1<<6 | param | (reg_1&07));
+        if ((mod_1 == 0 && reg_1 == 5) || mod_1 == 2) {
+                /* ??? should this be protected by a call to "small" ??? */
 #ifdef RELOCATION
-		RELOMOVE(relonami, rel_1);
-		newrelo(exp_1.typ, RELO4);
+                RELOMOVE(relonami, rel_1);
+                newrelo(exp_1.typ, RELO4);
 #endif
-		emit4((long)(exp_1.val));
-	}
-	else if (mod_1 == 1) {
-		emit1((int)(exp_1.val));
-	}
+                emit4((long)(exp_1.val));
+        }
+        else if (mod_1 == 1) {
+                emit1((int)(exp_1.val));
+        }
 }
 
 void ea_2(int param) {
 
-	op_1 = op_2;
-	RELOMOVE(rel_1, rel_2);
-	ea_1(param);
+        op_1 = op_2;
+        RELOMOVE(rel_1, rel_2);
+        ea_1(param);
 }
 
 int checkscale(valu_t val)
 {
-	int v = val;
+        int v = val;
 
-	if (! address_long) {
-		serror("scaling not allowed in 16-bit mode");
-		return 0;
-	}
-	if (v != val) v = 0;
-	switch(v) {
-	case 1:
-		return 0;
-	case 2:
-		return 1 << 6;
-	case 4:
-		return 2 << 6;
-	case 8:
-		return 3 << 6;
-	default:
-		serror("bad scale");
-		return 0;
-	}
-	/*NOTREACHED*/
+        if (! address_long) {
+                serror("scaling not allowed in 16-bit mode");
+                return 0;
+        }
+        if (v != val) v = 0;
+        switch(v) {
+        case 1:
+                return 0;
+        case 2:
+                return 1 << 6;
+        case 4:
+                return 2 << 6;
+        case 8:
+                return 3 << 6;
+        default:
+                serror("bad scale");
+                return 0;
+        }
+        /*NOTREACHED*/
 }
 
 void reverse(void) {
-	struct operand op;
+        struct operand op;
 #ifdef RELOCATION
-	int r = rel_1;
+        int r = rel_1;
 
-	rel_1 = rel_2; rel_2 = r;
+        rel_1 = rel_2; rel_2 = r;
 #endif
-	op = op_1; op_1 = op_2; op_2 = op;
+        op = op_1; op_1 = op_2; op_2 = op;
 }
 
 void badsyntax(void)
 {
 
-	serror("bad operands");
+        serror("bad operands");
 }
 
 void regsize(int sz)
 {
-	register int bit;
+        register int bit;
 
-	bit = (sz&1) ? 0 : IS_R8;
-	if ((is_reg(reg_1) && (reg_1 & IS_R8) != bit) ||
-	    (is_reg(reg_2) && (reg_2 & IS_R8) != bit)) 
-		serror("register error");
-	if (! address_long) {
-		reg_1 &= ~010;
-		reg_2 &= ~010;
-	}
+        bit = (sz&1) ? 0 : IS_R8;
+        if ((is_reg(reg_1) && (reg_1 & IS_R8) != bit) ||
+            (is_reg(reg_2) && (reg_2 & IS_R8) != bit)) 
+                serror("register error");
+        if (! address_long) {
+                reg_1 &= ~010;
+                reg_2 &= ~010;
+        }
 }
 
 void indexed(void) {
-	if (address_long) {
-		mod_2 = 0;
-		if (sib_2 == -1)
-			serror("register error");
-		if (rm_2 == 0 && reg_2 == 4) {
-			/* base register sp, no index register; use
-		   	   indexed mode without index register
-			*/
-			rm_2 = 04;
-			sib_2 = 044;
-		}
-		if (reg_2 == 015) {
-			reg_2 = 05;
-			return;
-		}
-		if (small(exp_2.typ == S_ABS && fitb(exp_2.val), 3)) {
-			if (small(exp_2.val == 0 && reg_2 != 5, 1)) {
-			}
-			else mod_2 = 01;
-		}
-		else	if (small(0, 1)) {
-		}
-		else mod_2 = 02;
-	}
-	else {
-        	if (reg_2 & ~7)
-                	serror("register error");
-        	if (small(exp_2.typ == S_ABS && fitb(exp_2.val), 1)) {
-			if (small(exp_2.val == 0 && reg_2 != 6, 1)) {
-			}
-			else reg_2 |= 0100;
-		}
-		else if (small(0, 1)) {
-		}
-		else reg_2 |= 0200;
-	}
+        if (address_long) {
+                mod_2 = 0;
+                if (sib_2 == -1)
+                        serror("register error");
+                if (rm_2 == 0 && reg_2 == 4) {
+                        /* base register sp, no index register; use
+                           indexed mode without index register
+                        */
+                        rm_2 = 04;
+                        sib_2 = 044;
+                }
+                if (reg_2 == 015) {
+                        reg_2 = 05;
+                        return;
+                }
+                if (small(exp_2.typ == S_ABS && fitb(exp_2.val), 3)) {
+                        if (small(exp_2.val == 0 && reg_2 != 5, 1)) {
+                        }
+                        else mod_2 = 01;
+                }
+                else    if (small(0, 1)) {
+                }
+                else mod_2 = 02;
+        }
+        else {
+                if (reg_2 & ~7)
+                        serror("register error");
+                if (small(exp_2.typ == S_ABS && fitb(exp_2.val), 1)) {
+                        if (small(exp_2.val == 0 && reg_2 != 6, 1)) {
+                        }
+                        else reg_2 |= 0100;
+                }
+                else if (small(0, 1)) {
+                }
+                else reg_2 |= 0200;
+        }
 }
 
 void ebranch(register int opc,expr_t exp)
 {
-	/*	Conditional branching; Full displacements are available
-		on the 80386, so the welknown trick with the reverse branch
-		over a jump is not needed here.
-		The only complication here is with the address size, which
-		can be set with a prefix. In this case, the user gets what
-		he asked for.
-	*/
-	register int sm;
-	register long dist;
-	int saving = address_long ? 4 : 2;
+        /*      Conditional branching; Full displacements are available
+                on the 80386, so the welknown trick with the reverse branch
+                over a jump is not needed here.
+                The only complication here is with the address size, which
+                can be set with a prefix. In this case, the user gets what
+                he asked for.
+        */
+        register int sm;
+        register long dist;
+        int saving = address_long ? 4 : 2;
 
-	if (opc == 0353) saving--;
-	dist = exp.val - (DOTVAL + 2);
-	if (pass == PASS_2 && dist > 0 && !(exp.typ & S_DOT))
-		dist -= DOTGAIN;
-	sm = dist > 0 ? fitb(dist-saving) : fitb(dist);
-	if ((exp.typ & ~S_DOT) != DOTTYP)
-		sm = 0;
-	if ((sm = small(sm,saving)) == 0) {
-		if (opc == 0353) {
-			emit1(0xe9);
-		}
-		else {
-			emit1(0xF);
-			emit1(opc | 0x80);
-		}
-		dist -= saving;
-		exp.val = dist;
-		adsize_exp(exp, RELPC);
-	}
-	else {
-		if (opc == 0353) {
-			emit1(opc);
-		}
-		else {
-			emit1(opc | 0x70);
-		}
-		emit1((int)dist);
-	}
+        if (opc == 0353) saving--;
+        dist = exp.val - (DOTVAL + 2);
+        if (pass == PASS_2 && dist > 0 && !(exp.typ & S_DOT))
+                dist -= DOTGAIN;
+        sm = dist > 0 ? fitb(dist-saving) : fitb(dist);
+        if ((exp.typ & ~S_DOT) != DOTTYP)
+                sm = 0;
+        if ((sm = small(sm,saving)) == 0) {
+                if (opc == 0353) {
+                        emit1(0xe9);
+                }
+                else {
+                        emit1(0xF);
+                        emit1(opc | 0x80);
+                }
+                dist -= saving;
+                exp.val = dist;
+                adsize_exp(exp, RELPC);
+        }
+        else {
+                if (opc == 0353) {
+                        emit1(opc);
+                }
+                else {
+                        emit1(opc | 0x70);
+                }
+                emit1((int)dist);
+        }
 }
 
 void branch(register int opc,expr_t exp)
 {
-	/*	LOOP, JCXZ, etc. branch instructions.
-		Here, the offset just must fit in a byte.
-	*/
-	register long dist;
+        /*      LOOP, JCXZ, etc. branch instructions.
+                Here, the offset just must fit in a byte.
+        */
+        register long dist;
 
-	dist = exp.val - (DOTVAL + 2);
-	if (pass == PASS_2 && dist > 0 && !(exp.typ & S_DOT))
-		dist -= DOTGAIN;
-	fit((exp.typ & ~S_DOT) == DOTTYP && fitb(dist));
-	emit1(opc);
-	emit1((int)dist);
+        dist = exp.val - (DOTVAL + 2);
+        if (pass == PASS_2 && dist > 0 && !(exp.typ & S_DOT))
+                dist -= DOTGAIN;
+        fit((exp.typ & ~S_DOT) == DOTTYP && fitb(dist));
+        emit1(opc);
+        emit1((int)dist);
 }
 
 void pushop(register int opc)
 {
 
-	regsize(1);
-	if (is_segreg(reg_1)) {
-		/* segment register */
-		if ((reg_1 & 07) <= 3)
-			emit1(6 | opc | (reg_1&7)<<3);
-		else {
-			emit1(0xF);
-			emit1(0200 | opc | ((reg_1&7)<<3));
-		}
-	} else if (is_reg(reg_1)) {
-		/* normal register */
-		emit1(0120 | opc<<3 | (reg_1&7));
-	} else if (opc == 0) {
-		if (is_expr(reg_1)) {
-			if (small(exp_1.typ == S_ABS && fitb(exp_1.val),
-				  operand_long ? 3 : 1)) {
-				emit1(0152);
-				emit1((int)(exp_1.val));
-			}
-			else {
-				emit1(0150);
-				RELOMOVE(relonami, rel_1);
-				opsize_exp(exp_1, 1);
-			}
-		}
-		else {
-			emit1(0377); ea_1(6<<3);
-		}
-	} else {
-		emit1(0217); ea_1(0<<3);
-	}
+        regsize(1);
+        if (is_segreg(reg_1)) {
+                /* segment register */
+                if ((reg_1 & 07) <= 3)
+                        emit1(6 | opc | (reg_1&7)<<3);
+                else {
+                        emit1(0xF);
+                        emit1(0200 | opc | ((reg_1&7)<<3));
+                }
+        } else if (is_reg(reg_1)) {
+                /* normal register */
+                emit1(0120 | opc<<3 | (reg_1&7));
+        } else if (opc == 0) {
+                if (is_expr(reg_1)) {
+                        if (small(exp_1.typ == S_ABS && fitb(exp_1.val),
+                                  operand_long ? 3 : 1)) {
+                                emit1(0152);
+                                emit1((int)(exp_1.val));
+                        }
+                        else {
+                                emit1(0150);
+                                RELOMOVE(relonami, rel_1);
+                                opsize_exp(exp_1, 1);
+                        }
+                }
+                else {
+                        emit1(0377); ea_1(6<<3);
+                }
+        } else {
+                emit1(0217); ea_1(0<<3);
+        }
 }
 
 void opsize_exp(expr_t exp, int nobyte)
 {
-	if (! nobyte) {
+        if (! nobyte) {
 #ifdef RELOCATION
-		newrelo(exp.typ, RELO1);
+                newrelo(exp.typ, RELO1);
 #endif
-		emit1((int)(exp.val));
-	}
-	else if (operand_long) {
+                emit1((int)(exp.val));
+        }
+        else if (operand_long) {
 #ifdef RELOCATION
-		newrelo(exp.typ, RELO4);
+                newrelo(exp.typ, RELO4);
 #endif
-		emit4((long)(exp.val));
-	}
-	else {
+                emit4((long)(exp.val));
+        }
+        else {
 #ifdef RELOCATION
-		newrelo(exp.typ, RELO2);
+                newrelo(exp.typ, RELO2);
 #endif
-		emit2((int)(exp.val));
-	}
+                emit2((int)(exp.val));
+        }
 }
 
 void adsize_exp(expr_t exp, int relpc)
 {
-	if (address_long) {
+        if (address_long) {
 #ifdef RELOCATION
-		newrelo(exp.typ, RELO4 | relpc);
+                newrelo(exp.typ, RELO4 | relpc);
 #endif
-		emit4((long)(exp.val));
-	}
-	else {
+                emit4((long)(exp.val));
+        }
+        else {
 #ifdef RELOCATION
-		newrelo(exp.typ, RELO2 | relpc);
+                newrelo(exp.typ, RELO2 | relpc);
 #endif
-		emit2((int)(exp.val));
-	}
+                emit2((int)(exp.val));
+        }
 }
 
 void addop(register int opc)
 {
 
-	regsize(opc);
-	if (is_reg(reg_2)) {
-		/*	Add register to register or memory */
-		emit1(opc); ea_1((reg_2&7)<<3);
-	} else if (is_acc(reg_1) && is_expr(reg_2)) {
-		/*	Add immediate to accumulator */
-		emit1(opc | 4);
-		RELOMOVE(relonami, rel_2);
-		opsize_exp(exp_2, (opc&1));
-	} else if (is_expr(reg_2)) {
-		/*	Add immediate to register or memory */
-		if ((opc&1) == 0) {
-			emit1(0200);
-		} else if (! small(exp_2.typ == S_ABS && fitb(exp_2.val),
-			   	   operand_long ? 3 : 1)) {
-			emit1(0201);
-		} else {
-			emit1(0203); opc &= ~1;
-		}
-		ea_1(opc & 070);
-		RELOMOVE(relonami, rel_2);
-		opsize_exp(exp_2, (opc&1));
-	} else if (is_reg(reg_1)) {
-		/*	Add register or memory to register */
-		emit1(opc | 2);
-		ea_2((reg_1&7)<<3);
-	} else
-		badsyntax();
+        regsize(opc);
+        if (is_reg(reg_2)) {
+                /*      Add register to register or memory */
+                emit1(opc); ea_1((reg_2&7)<<3);
+        } else if (is_acc(reg_1) && is_expr(reg_2)) {
+                /*      Add immediate to accumulator */
+                emit1(opc | 4);
+                RELOMOVE(relonami, rel_2);
+                opsize_exp(exp_2, (opc&1));
+        } else if (is_expr(reg_2)) {
+                /*      Add immediate to register or memory */
+                if ((opc&1) == 0) {
+                        emit1(0200);
+                } else if (! small(exp_2.typ == S_ABS && fitb(exp_2.val),
+                                   operand_long ? 3 : 1)) {
+                        emit1(0201);
+                } else {
+                        emit1(0203); opc &= ~1;
+                }
+                ea_1(opc & 070);
+                RELOMOVE(relonami, rel_2);
+                opsize_exp(exp_2, (opc&1));
+        } else if (is_reg(reg_1)) {
+                /*      Add register or memory to register */
+                emit1(opc | 2);
+                ea_2((reg_1&7)<<3);
+        } else
+                badsyntax();
 }
 
 void rolop(register int opc)
 {
-	register int oreg;
+        register int oreg;
 
-	oreg = reg_2;
-	reg_2 = reg_1;
-	regsize(opc);
-	if (oreg == (IS_R8 | 1 | (address_long ? 0 : 0300))) {
-		/* cl register */
-		emit1(0322 | (opc&1)); ea_1(opc&070);
-	} else if (is_expr(oreg)) {
-	    if (small(exp_2.typ == S_ABS && exp_2.val == 1, 1)) {
-		/* shift by 1 */
-		emit1(0320 | (opc&1)); ea_1(opc&070);
-	    } else {
-		/* shift by byte count */
-		emit1(0300 | (opc & 1)); 
-		ea_1(opc & 070);
+        oreg = reg_2;
+        reg_2 = reg_1;
+        regsize(opc);
+        if (oreg == (IS_R8 | 1 | (address_long ? 0 : 0300))) {
+                /* cl register */
+                emit1(0322 | (opc&1)); ea_1(opc&070);
+        } else if (is_expr(oreg)) {
+            if (small(exp_2.typ == S_ABS && exp_2.val == 1, 1)) {
+                /* shift by 1 */
+                emit1(0320 | (opc&1)); ea_1(opc&070);
+            } else {
+                /* shift by byte count */
+                emit1(0300 | (opc & 1)); 
+                ea_1(opc & 070);
 #ifdef RELOCATION
-		RELOMOVE(relonami, rel_2);
-		newrelo(exp_2.typ, RELO1);
+                RELOMOVE(relonami, rel_2);
+                newrelo(exp_2.typ, RELO1);
 #endif
-		emit1((int)(exp_2.val));
-	    }
-	}
-	else
-		badsyntax();
+                emit1((int)(exp_2.val));
+            }
+        }
+        else
+                badsyntax();
 }
 
 void incop(register int opc)
 {
 
-	regsize(opc);
-	if ((opc&1) && is_reg(reg_1)) {
-		/* word register */
-		emit1(0100 | (opc&010) | (reg_1&7));
-	} else {
-		emit1(0376 | (opc&1));
-		ea_1(opc & 010);
-	}
+        regsize(opc);
+        if ((opc&1) && is_reg(reg_1)) {
+                /* word register */
+                emit1(0100 | (opc&010) | (reg_1&7));
+        } else {
+                emit1(0376 | (opc&1));
+                ea_1(opc & 010);
+        }
 }
 
 void callop(register int opc)
 {
 
-	regsize(1);
-	if (is_expr(reg_1)) {
-		if (opc == (040+(0351<<8))) {
-			RELOMOVE(relonami, rel_1);
-			ebranch(0353,exp_1);
-		} else {
-			exp_1.val -= (DOTVAL+3 + (address_long ? 2 : 0));
-			emit1(opc>>8);
-			RELOMOVE(relonami, rel_1);
-			adsize_exp(exp_1, RELPC);
-		}
-	} else {
-		emit1(0377); ea_1(opc&070);
-	}
+        regsize(1);
+        if (is_expr(reg_1)) {
+                if (opc == (040+(0351<<8))) {
+                        RELOMOVE(relonami, rel_1);
+                        ebranch(0353,exp_1);
+                } else {
+                        exp_1.val -= (DOTVAL+3 + (address_long ? 2 : 0));
+                        emit1(opc>>8);
+                        RELOMOVE(relonami, rel_1);
+                        adsize_exp(exp_1, RELPC);
+                }
+        } else {
+                emit1(0377); ea_1(opc&070);
+        }
 }
 
 void xchg(register int opc)
 {
 
-	regsize(opc);
-	if (! is_reg(reg_1) || is_acc(reg_2)) {
-		reverse();
-	}
-	if (opc == 1 && is_acc(reg_1) && is_reg(reg_2)) {
-		emit1(0220 | (reg_2&7));
-	} else if (is_reg(reg_1)) {
-		emit1(0206 | opc); ea_2((reg_1&7)<<3);
-	} else
-		badsyntax();
+        regsize(opc);
+        if (! is_reg(reg_1) || is_acc(reg_2)) {
+                reverse();
+        }
+        if (opc == 1 && is_acc(reg_1) && is_reg(reg_2)) {
+                emit1(0220 | (reg_2&7));
+        } else if (is_reg(reg_1)) {
+                emit1(0206 | opc); ea_2((reg_1&7)<<3);
+        } else
+                badsyntax();
 }
 
 void test(register int opc)
 {
 
-	regsize(opc);
-	if (is_reg(reg_2) || is_expr(reg_1))
-		reverse();
-	if (is_expr(reg_2)) {
-		if (is_acc(reg_1)) {
-			emit1(0250 | opc);
-			RELOMOVE(relonami, rel_2);
-			opsize_exp(exp_2, (opc&1));
-		}
-		else {
-			emit1(0366 | opc);
-			ea_1(0<<3);
-			RELOMOVE(relonami, rel_2);
-			opsize_exp(exp_2, (opc&1));
-		}
-	} else if (is_reg(reg_1)) {
-		emit1(0204 | opc); ea_2((reg_1&7)<<3);
-	} else
-		badsyntax();
+        regsize(opc);
+        if (is_reg(reg_2) || is_expr(reg_1))
+                reverse();
+        if (is_expr(reg_2)) {
+                if (is_acc(reg_1)) {
+                        emit1(0250 | opc);
+                        RELOMOVE(relonami, rel_2);
+                        opsize_exp(exp_2, (opc&1));
+                }
+                else {
+                        emit1(0366 | opc);
+                        ea_1(0<<3);
+                        RELOMOVE(relonami, rel_2);
+                        opsize_exp(exp_2, (opc&1));
+                }
+        } else if (is_reg(reg_1)) {
+                emit1(0204 | opc); ea_2((reg_1&7)<<3);
+        } else
+                badsyntax();
 }
 
 void mov(register int opc)
 {
 
-	regsize(opc);
-	if (is_segreg(reg_1)) {
-		/* to segment register */
-		emit1(0216); ea_2((reg_1&07)<<3);
-	} else if (is_segreg(reg_2)) {
-		/* from segment register */
-		emit1(0214); ea_1((reg_2&07)<<3);
-	} else if (is_expr(reg_2)) {
-		/* from immediate */
-		if (is_reg(reg_1)) {
-			/* to register */
-			emit1(0260 | opc<<3 | (reg_1&7)); 
-		} else {
-			/* to memory */
-			emit1(0306 | opc); ea_1(0<<3); 
-		}
-		RELOMOVE(relonami, rel_2);
-		opsize_exp(exp_2, (opc&1));
-	} else if (rm_1 == 05 && is_acc(reg_2)) {
-		/* from accumulator to memory  (displacement) */
-		emit1(0242 | opc);
-		RELOMOVE(relonami, rel_1);
-		adsize_exp(exp_1, 0);
-	} else if (rm_2 == 05 && is_acc(reg_1)) {
-		/* from memory (displacement) to accumulator */
-		emit1(0240 | opc);
-		RELOMOVE(relonami, rel_2);
-		adsize_exp(exp_2, 0);
-	} else if (is_reg(reg_2)) {
-		/* from register to memory or register */
-		emit1(0210 | opc); ea_1((reg_2&07)<<3);
-	} else if (is_reg(reg_1)) {
-		/* from memory or register to register */
-		emit1(0212 | opc); ea_2((reg_1&07)<<3);
-	} else
-		badsyntax();
+        regsize(opc);
+        if (is_segreg(reg_1)) {
+                /* to segment register */
+                emit1(0216); ea_2((reg_1&07)<<3);
+        } else if (is_segreg(reg_2)) {
+                /* from segment register */
+                emit1(0214); ea_1((reg_2&07)<<3);
+        } else if (is_expr(reg_2)) {
+                /* from immediate */
+                if (is_reg(reg_1)) {
+                        /* to register */
+                        emit1(0260 | opc<<3 | (reg_1&7)); 
+                } else {
+                        /* to memory */
+                        emit1(0306 | opc); ea_1(0<<3); 
+                }
+                RELOMOVE(relonami, rel_2);
+                opsize_exp(exp_2, (opc&1));
+        } else if (rm_1 == 05 && is_acc(reg_2)) {
+                /* from accumulator to memory  (displacement) */
+                emit1(0242 | opc);
+                RELOMOVE(relonami, rel_1);
+                adsize_exp(exp_1, 0);
+        } else if (rm_2 == 05 && is_acc(reg_1)) {
+                /* from memory (displacement) to accumulator */
+                emit1(0240 | opc);
+                RELOMOVE(relonami, rel_2);
+                adsize_exp(exp_2, 0);
+        } else if (is_reg(reg_2)) {
+                /* from register to memory or register */
+                emit1(0210 | opc); ea_1((reg_2&07)<<3);
+        } else if (is_reg(reg_1)) {
+                /* from memory or register to register */
+                emit1(0212 | opc); ea_2((reg_1&07)<<3);
+        } else
+                badsyntax();
 }
 
 void extshft(int opc, int reg)
 {
-	int oreg2 = reg_2;
+        int oreg2 = reg_2;
 
-	reg_2 = reg_1;
-	regsize(1);
+        reg_2 = reg_1;
+        regsize(1);
 
-	emit1(0xF);
-	if (oreg2 == (IS_R8 | 1 | (address_long ? 0 : 0300))) {
-		/* cl register */
-		emit1(opc|1);
-		ea_1(reg << 3);
-	}
-	else if (is_expr(oreg2)) {
-		emit1(opc);
-		ea_1(reg << 3);
+        emit1(0xF);
+        if (oreg2 == (IS_R8 | 1 | (address_long ? 0 : 0300))) {
+                /* cl register */
+                emit1(opc|1);
+                ea_1(reg << 3);
+        }
+        else if (is_expr(oreg2)) {
+                emit1(opc);
+                ea_1(reg << 3);
 #ifdef RELOCATION
-		RELOMOVE(relonami, rel_2);
-		newrelo(exp_2.typ, RELO1);
+                RELOMOVE(relonami, rel_2);
+                newrelo(exp_2.typ, RELO1);
 #endif
-		emit1((int)(exp_2.val));
-	}
-	else	badsyntax();
+                emit1((int)(exp_2.val));
+        }
+        else    badsyntax();
 }
 
 void bittestop(int opc)
 {
-	regsize(1);
-	emit1(0xF);
-	if (is_expr(reg_2)) {
-		emit1(0272);
-		ea_1(opc << 3);
+        regsize(1);
+        emit1(0xF);
+        if (is_expr(reg_2)) {
+                emit1(0272);
+                ea_1(opc << 3);
 #ifdef RELOCATION
-		RELOMOVE(relonami, rel_2);
-		newrelo(exp_2.typ, RELO1);
+                RELOMOVE(relonami, rel_2);
+                newrelo(exp_2.typ, RELO1);
 #endif
-		emit1((int)(exp_2.val));
-	}
-	else if (is_reg(reg_2)) {
-		emit1(0203 | (opc<<3));
-		ea_1((reg_2&7)<<3);
-	}
-	else	badsyntax();
+                emit1((int)(exp_2.val));
+        }
+        else if (is_reg(reg_2)) {
+                emit1(0203 | (opc<<3));
+                ea_1((reg_2&7)<<3);
+        }
+        else    badsyntax();
 }
 
 void imul(int reg)
 {
-	/*	This instruction is more elaborate on the 80386. Its most
-		general form is:
-			imul reg, reg_or_mem, immediate.
-		This is the form processed here.
-	*/
-	regsize(1);
-	if (is_expr(reg_1)) {
-		/* To also handle
-			imul reg, immediate, reg_or_mem
-		*/
-		reverse();
-	}
-	if (is_expr(reg_2)) {
-		/* The immediate form; two cases: */
-		if (small(exp_2.typ == S_ABS && fitb(exp_2.val),
-			  operand_long ? 3 : 1)) {
-			/* case 1: 1 byte encoding of immediate */
-			emit1(0153);
-			ea_1((reg & 07) << 3);
-			emit1((int)(exp_2.val));
-		}
-		else {
-			/* case 2: WORD or DWORD encoding of immediate */
-			emit1(0151);
-			ea_1((reg & 07) << 3);
-			RELOMOVE(relonami, rel_2);
-			opsize_exp(exp_2, 1);
-		}
-	}
-	else if (is_reg(reg_1) && ((reg_1&7) == (reg & 07))) {
-		/* the "reg" field and the "reg_or_mem" field are the same,
-		   and the 3rd operand is not an immediate ...
-		*/
-		if (reg == 0) {
-			/* how lucky we are, the target is the ax register */
-			/* However, we cannot make an optimization for f.i.
-				imul eax, blablabla
-			   because the latter does not affect edx, whereas
-				imul blablabla
-			   does! Therefore, "reg" is or-ed with 0x10 in the
-			   former case, so that the test above fails.
-			*/
-			emit1(0367);
-			ea_2(050);
-		}
-		else {
-			/* another register ... */
-			emit1(0xF);
-			emit1(0257);
-			ea_2((reg & 07) << 3);
-		}
-	}
-	else badsyntax();
+        /*      This instruction is more elaborate on the 80386. Its most
+                general form is:
+                        imul reg, reg_or_mem, immediate.
+                This is the form processed here.
+        */
+        regsize(1);
+        if (is_expr(reg_1)) {
+                /* To also handle
+                        imul reg, immediate, reg_or_mem
+                */
+                reverse();
+        }
+        if (is_expr(reg_2)) {
+                /* The immediate form; two cases: */
+                if (small(exp_2.typ == S_ABS && fitb(exp_2.val),
+                          operand_long ? 3 : 1)) {
+                        /* case 1: 1 byte encoding of immediate */
+                        emit1(0153);
+                        ea_1((reg & 07) << 3);
+                        emit1((int)(exp_2.val));
+                }
+                else {
+                        /* case 2: WORD or DWORD encoding of immediate */
+                        emit1(0151);
+                        ea_1((reg & 07) << 3);
+                        RELOMOVE(relonami, rel_2);
+                        opsize_exp(exp_2, 1);
+                }
+        }
+        else if (is_reg(reg_1) && ((reg_1&7) == (reg & 07))) {
+                /* the "reg" field and the "reg_or_mem" field are the same,
+                   and the 3rd operand is not an immediate ...
+                */
+                if (reg == 0) {
+                        /* how lucky we are, the target is the ax register */
+                        /* However, we cannot make an optimization for f.i.
+                                imul eax, blablabla
+                           because the latter does not affect edx, whereas
+                                imul blablabla
+                           does! Therefore, "reg" is or-ed with 0x10 in the
+                           former case, so that the test above fails.
+                        */
+                        emit1(0367);
+                        ea_2(050);
+                }
+                else {
+                        /* another register ... */
+                        emit1(0xF);
+                        emit1(0257);
+                        ea_2((reg & 07) << 3);
+                }
+        }
+        else badsyntax();
 }
+
+// vim: ts=8 sw=8 et
+
diff --git a/mach/proto/as/comm7.c b/mach/proto/as/comm7.c
index 9b93139d4..06e11042b 100644
--- a/mach/proto/as/comm7.c
+++ b/mach/proto/as/comm7.c
@@ -86,6 +86,9 @@ char* remember(char* s)
 
 int combine(int typ1, int typ2, int op)
 {
+	typ1 &= ~S_VAR;
+	typ2 &= ~S_VAR;
+
 	switch (op)
 	{
 		case '+':
diff --git a/plat/msdos/include/ack/plat.h b/plat/msdos/include/ack/plat.h
new file mode 100644
index 000000000..4343f1cf8
--- /dev/null
+++ b/plat/msdos/include/ack/plat.h
@@ -0,0 +1,11 @@
+/* $Source$
+ * $State$
+ * $Revision$
+ */
+
+#ifndef _ACK_PLAT_H
+#define _ACK_PLAT_H
+
+#define ACKCONF_WANT_O_TEXT_O_BINARY 1
+
+#endif
diff --git a/plat/msdos/include/build.lua b/plat/msdos/include/build.lua
new file mode 100644
index 000000000..6ae480041
--- /dev/null
+++ b/plat/msdos/include/build.lua
@@ -0,0 +1,24 @@
+include("plat/build.lua")
+
+headermap = {}
+packagemap = {}
+
+local function addheader(h)
+	headermap[h] = "./"..h
+	packagemap["$(PLATIND)/msdos86/include/"..h] = "./"..h
+end
+
+addheader("ack/plat.h")
+addheader("sys/types.h")
+
+acklibrary {
+	name = "headers",
+	hdrs = headermap
+}
+
+installable {
+	name = "pkg",
+	map = packagemap
+}
+
+
diff --git a/plat/msdos/include/sys/types.h b/plat/msdos/include/sys/types.h
new file mode 100644
index 000000000..005f48eb0
--- /dev/null
+++ b/plat/msdos/include/sys/types.h
@@ -0,0 +1,9 @@
+#ifndef _SYS_TYPES_H
+#define _SYS_TYPES_H
+
+typedef long pid_t;
+typedef int mode_t;
+typedef long time_t;
+typedef long suseconds_t;
+
+#endif
diff --git a/plat/msdos/libsys/build.lua b/plat/msdos/libsys/build.lua
new file mode 100644
index 000000000..d808fe894
--- /dev/null
+++ b/plat/msdos/libsys/build.lua
@@ -0,0 +1,28 @@
+bundle {
+	name = "srcs",
+	srcs = {
+		"./creat.c",
+		"./gettimeofday.c",
+		"./kill.c",
+		"./lseek.c",
+		"./open.c",
+		"./read.c",
+		"./setmode.c",
+		"./signal.c",
+		"./sys_fdmodes.c",
+		"./sys_getmode.c",
+		"./sys_initmain.c",
+		"./sys_iseof.c",
+		"./sys_seteof.c",
+		"./sys_seterrno.c",
+		"./sys_setmode.c",
+		"./write.c",
+	}
+}
+
+bundle {
+	name = "headers",
+	srcs = {
+		"./libsys.h"
+	}
+}
diff --git a/plat/msdos86/libsys/creat.c b/plat/msdos/libsys/creat.c
similarity index 100%
rename from plat/msdos86/libsys/creat.c
rename to plat/msdos/libsys/creat.c
diff --git a/plat/msdos86/libsys/gettimeofday.c b/plat/msdos/libsys/gettimeofday.c
similarity index 100%
rename from plat/msdos86/libsys/gettimeofday.c
rename to plat/msdos/libsys/gettimeofday.c
diff --git a/plat/msdos86/libsys/kill.c b/plat/msdos/libsys/kill.c
similarity index 100%
rename from plat/msdos86/libsys/kill.c
rename to plat/msdos/libsys/kill.c
diff --git a/plat/msdos86/libsys/libsys.h b/plat/msdos/libsys/libsys.h
similarity index 100%
rename from plat/msdos86/libsys/libsys.h
rename to plat/msdos/libsys/libsys.h
diff --git a/plat/msdos86/libsys/lseek.c b/plat/msdos/libsys/lseek.c
similarity index 100%
rename from plat/msdos86/libsys/lseek.c
rename to plat/msdos/libsys/lseek.c
diff --git a/plat/msdos86/libsys/open.c b/plat/msdos/libsys/open.c
similarity index 100%
rename from plat/msdos86/libsys/open.c
rename to plat/msdos/libsys/open.c
diff --git a/plat/msdos86/libsys/read.c b/plat/msdos/libsys/read.c
similarity index 71%
rename from plat/msdos86/libsys/read.c
rename to plat/msdos/libsys/read.c
index 5075958bd..bed9fcd14 100644
--- a/plat/msdos86/libsys/read.c
+++ b/plat/msdos/libsys/read.c
@@ -5,6 +5,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 #include <errno.h>
 #include <unistd.h>
@@ -16,9 +17,7 @@ ssize_t read(int fd, void* buffer, size_t count)
 	ssize_t r, tot;
 	size_t left;
 	int eof = 0;
-
-	if (!count || _sys_getmode(fd) == O_BINARY)
-		return _sys_rawread(fd, buffer, count);
+	bool text = _sys_getmode(fd) == O_TEXT;
 
 	if (_sys_iseof(fd))
 		return 0;
@@ -47,33 +46,36 @@ ssize_t read(int fd, void* buffer, size_t count)
 		if (r <= 0)
 			return tot ? tot : r;
 
-		q = memchr(p, 0x1a, (size_t)r);
-		if (q)
+		if (text)
 		{
-			_sys_rawlseek(fd, (off_t)(q - p) - r, SEEK_CUR);
-			r = q - p;
-			eof = 1;
-			_sys_seteof(fd, 1);
-		}
-
-		q = memchr(p, '\r', (size_t)r);
-		if (!q)
-			return tot + r;
-
-		tot += q - p;
-		left = r - (q + 1 - p);
-		p = q;
-		++q;
-
-		while (left)
-		{
-			char c = *q++;
-			if (c != '\r')
+			q = memchr(p, 0x1a, (size_t)r);
+			if (q)
 			{
-				*p++ = c;
-				++tot;
+				_sys_rawlseek(fd, (off_t)(q - p) - r, SEEK_CUR);
+				r = q - p;
+				eof = 1;
+				_sys_seteof(fd, 1);
+			}
+
+			q = memchr(p, '\r', (size_t)r);
+			if (!q)
+				return tot + r;
+
+			tot += q - p;
+			left = r - (q + 1 - p);
+			p = q;
+			++q;
+
+			while (left)
+			{
+				char c = *q++;
+				if (c != '\r')
+				{
+					*p++ = c;
+					++tot;
+				}
+				--left;
 			}
-			--left;
 		}
 	} while (tot < count && !eof && _sys_isreadyr(fd));
 
diff --git a/plat/msdos86/libsys/setmode.c b/plat/msdos/libsys/setmode.c
similarity index 100%
rename from plat/msdos86/libsys/setmode.c
rename to plat/msdos/libsys/setmode.c
diff --git a/plat/msdos86/libsys/signal.c b/plat/msdos/libsys/signal.c
similarity index 100%
rename from plat/msdos86/libsys/signal.c
rename to plat/msdos/libsys/signal.c
diff --git a/plat/msdos86/libsys/sys_fdmodes.c b/plat/msdos/libsys/sys_fdmodes.c
similarity index 100%
rename from plat/msdos86/libsys/sys_fdmodes.c
rename to plat/msdos/libsys/sys_fdmodes.c
diff --git a/plat/msdos86/libsys/sys_getmode.c b/plat/msdos/libsys/sys_getmode.c
similarity index 100%
rename from plat/msdos86/libsys/sys_getmode.c
rename to plat/msdos/libsys/sys_getmode.c
diff --git a/plat/msdos86/libsys/sys_initmain.c b/plat/msdos/libsys/sys_initmain.c
similarity index 100%
rename from plat/msdos86/libsys/sys_initmain.c
rename to plat/msdos/libsys/sys_initmain.c
diff --git a/plat/msdos86/libsys/sys_iseof.c b/plat/msdos/libsys/sys_iseof.c
similarity index 100%
rename from plat/msdos86/libsys/sys_iseof.c
rename to plat/msdos/libsys/sys_iseof.c
diff --git a/plat/msdos86/libsys/sys_seteof.c b/plat/msdos/libsys/sys_seteof.c
similarity index 100%
rename from plat/msdos86/libsys/sys_seteof.c
rename to plat/msdos/libsys/sys_seteof.c
diff --git a/plat/msdos86/libsys/sys_seterrno.c b/plat/msdos/libsys/sys_seterrno.c
similarity index 100%
rename from plat/msdos86/libsys/sys_seterrno.c
rename to plat/msdos/libsys/sys_seterrno.c
diff --git a/plat/msdos86/libsys/sys_setmode.c b/plat/msdos/libsys/sys_setmode.c
similarity index 100%
rename from plat/msdos86/libsys/sys_setmode.c
rename to plat/msdos/libsys/sys_setmode.c
diff --git a/plat/msdos/libsys/write.c b/plat/msdos/libsys/write.c
new file mode 100644
index 000000000..cfc764246
--- /dev/null
+++ b/plat/msdos/libsys/write.c
@@ -0,0 +1,74 @@
+/* $Source$
+ * $State$
+ * $Revision$
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include "libsys.h"
+
+ssize_t write(int fd, void* buffer, size_t count)
+{
+	static const char crlf[2] = "\r\n";
+	int i;
+	char *p, *q;
+	size_t left, n;
+	ssize_t r, tot;
+
+	if (!count)
+		return 0;
+
+	p = buffer;
+	left = count;
+	tot = 0;
+
+	if (_sys_getmode(fd) == O_BINARY)
+	{
+		while (left)
+		{
+			r = _sys_rawwrite(fd, p, left);
+			if (r <= 0)
+				return tot ? tot : r;
+			tot += r;
+			p += r;
+			left -= r;
+		}
+	}
+	else
+	{
+		/* If the file descriptor is an O_TEXT fd, translate LFs to CRLFs. */
+		while (left)
+		{
+			q = memchr(p, '\n', left);
+			if (!q)
+				return _sys_rawwrite(fd, p, left);
+
+			n = q - p;
+			if (n)
+			{
+				r = _sys_rawwrite(fd, p, n);
+				if (r <= 0)
+					return tot ? tot : r;
+				tot += r;
+				p += r;
+				left -= r;
+				if (r != n)
+					break;
+			}
+
+			r = _sys_rawwrite(fd, crlf, sizeof crlf);
+			if (r != 2)
+			{
+				if (r > 0)
+					r = 0;
+				return tot ? tot : r;
+			}
+			++tot;
+			++p;
+			--left;
+		}
+	}
+	return tot;
+}
diff --git a/plat/msdos386/README b/plat/msdos386/README
new file mode 100644
index 000000000..0a52528a6
--- /dev/null
+++ b/plat/msdos386/README
@@ -0,0 +1,24 @@
+The msdos386 platform
+=====================
+
+msdos386 is an i386-based BSP that produces DPMI DOS executables. It should
+have the same functionality as msdos86 (as the libc is all the same code), but
+has been much less well tested.
+
+The code runs in flat 32-bit mode, so normal 32-bit pointers work with no
+worries about segmentation. It requires a DPMI host to run; it was tested with
+CWSDPMI. It will _not_ automatically load the host --- you need to manually
+install the DPMI hsot first.
+
+IEEE floating point is available, but requires an FPU.
+
+
+Example command line
+====================
+
+ack -mmsdos386 -O -o msdos386.exe examples/paranoia.c
+
+
+David Given
+dg@cowlark.com
+
diff --git a/plat/msdos386/boot.s b/plat/msdos386/boot.s
new file mode 100644
index 000000000..6e1b02add
--- /dev/null
+++ b/plat/msdos386/boot.s
@@ -0,0 +1,236 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+#define STACK_BUFFER 128 /* number of bytes to leave for stack */
+
+! g 18b to break at the retf before coming here
+begtext:
+    ! On entry, the stub has cs and ds pointing at the 32-bit
+    ! segment, but ss is still pointing at the 16-bit segment.
+    !
+    !   ax: pmode code segment of stub
+    !   bx: pmode data segment of stub
+    !   cx: rmode segment of stub
+    !   dx: pointer to realloc routine (in stub)e
+    !   si: pointer to interrupt routine (in stub)
+    !   di: pointer to transfer buffer (in stub)
+
+    ! Resize the segment to include the BSS.
+
+    o16 cseg mov (realloc_ptr+4), ax
+    cseg mov (realloc_ptr+0), edx
+    cseg o16 mov (pmode_cs), ax
+    cseg o16 mov (pmode_ds), bx
+    cseg o16 mov (rmode), cx
+    cseg o16 mov (interrupt_ptr+4), ax
+    cseg mov (interrupt_ptr+0), esi
+    cseg o16 mov (transfer_buffer_ptr), di
+
+    mov eax, __end
+    cseg callf (realloc_ptr)
+
+    ! Clear BSS.
+
+    mov edi, begbss
+    mov ecx, endbss+1
+    sub ecx, edi
+    shr ecx, 1
+    xor eax, eax
+    cld
+    rep stosw
+
+    ! It's now safe to switch stacks.
+
+    cli
+    mov eax, ds
+    mov ss, eax
+    mov sp, .stack
+    sti
+
+    ! Create a handle for low 1MB access.
+
+    o16 mov ax, 0x0000
+    o16 mov cx, 1
+    int 0x31                    ! allocate LDT
+    mov es, ax
+    o16 mov bx, ax
+    o16 mov (.doshandle), bx
+    mov es, bx
+
+    xor ecx, ecx
+    xor edx, edx
+    o16 mov ax, 0x0007
+    int 0x31                    ! set base address to 0
+    o16 mov cx, 0x0010
+    o16 mov ax, 0x0008
+    int 0x31                    ! set limit to 1MB
+
+    mov cx, ds
+    and cx, 3
+    shl cx, 5
+    or cx, 0xc093               ! 32-bit, big, data, r/w, expand-up
+    mov ax, 0x0009
+    int 0x31                    ! set descriptor access rights
+
+    ! Locate the PSP.
+    
+    movb ah, 0x62
+    int 0x21
+    movzx esi, bx
+    shl esi, 4                  ! convert to linear address
+
+    ! Copy the whole thing into 32-bit memory.
+
+    mov ecx, 0x100/4
+    mov edi, _psp
+    cld
+1:
+    eseg lods
+    mov (edi), eax
+    add edi, 4
+    loop 1b
+
+    ! Find the environment.
+
+    mov es, (_psp + 0x002C)     ! converted to pmode segment
+    
+    ! Count the size of the environment variable block.
+
+    xorb al, al                 ! byte to test for
+    xor edi, edi
+    xor edx, edx
+    cld
+    mov ecx, -1
+    scasb
+    jz 2f                       ! empty environment
+1:
+    repnz scasb
+    inc edx
+    scasb
+    jnz 1b
+2:
+    add edi, 2                  ! skip the mysterious word
+    repnz scasb                 ! program name
+
+    ! Copy the whole environment block onto the stack.
+
+    mov esi, edi
+    add esi, 3
+    and esi, ~3                 ! round up
+    jz empty_environment
+    mov ecx, esi
+    shr ecx, 2                  ! number of dwords
+    std
+    sub esi, 4
+1:
+    eseg lods
+    push eax
+    loop 1b
+empty_environment:
+    mov ecx, esp                ! environment data
+
+    ! Reset DF and es properly.
+
+    cld
+    push ss
+    pop es
+
+    ! Reserve space for argc and the argv and envp pointers on the
+    ! stack.  These will be passed to __m_a_i_n later.
+
+    sub esp, 3*4
+    mov eax, esp
+
+    ! Build up argc, argv[], and envp[].
+    push eax            ! output buffer for argc, argv, envp
+    push 3              ! MS-DOS version
+    push ecx            ! env. string data
+    push edx            ! count of env. vars.
+    push _psp+0x80      ! raw command line
+    call __sys_initmain
+    add esp, 5*4
+
+    ! Bail out if something went wrong.
+    test eax, eax
+    jnz no_room
+
+    ! argc, argv, and envp are now at the stack top.  Now go.
+    call __m_a_i_n
+    add sp, 3*4
+    push ax
+    call _exit
+
+no_room:
+    mov dx, no_room_msg
+    !call dos_msg
+    movb al, -1
+    jmp al_exit
+
+    ! Exit.
+.define __exit
+.extern __exit
+.define EXIT
+.extern EXIT
+__exit:
+EXIT:
+    pop bx
+    pop ax
+al_exit:
+    movb ah, 0x4c
+    int 0x21
+
+    ! These must be in the code segment due to bootstrap issues.
+realloc_ptr:         .space 6 ! far
+interrupt_ptr:       .space 6 ! far
+transfer_buffer_ptr: .space 2 ! near
+rmode:               .space 2
+pmode_cs:            .space 2
+pmode_ds:            .space 2
+
+.define realloc_ptr
+.define interrupt_ptr
+.define rmode
+.define pmode_cs
+.define pmode_ds
+.define transfer_buffer_ptr
+
+! Define symbols at the beginning of our various segments, so that we can find
+! them. (Except .text, which has already been done.)
+
+.define begtext, begdata, begbss
+.sect .data;       begdata:
+.sect .rom;        begrom:
+.sect .bss;        begbss:
+
+.sect .rom
+
+! Some text messages.
+bad_sys_msg: .ascii 'Bad DOS$'
+no_room_msg: .ascii 'No room$'
+
+! Some magic data. All EM systems need these.
+
+.define .trppc, .ignmask, _errno
+.comm .trppc, 4
+.comm .ignmask, 4
+.comm _errno, 4
+
+.comm .doshandle, 2
+.comm _psp, 256
+
+.sect .bss
+    .space 32*1024
+.stack:
+
+! vim: ts=4 sw=4 et ft=asm
+
diff --git a/plat/msdos386/build-pkg.lua b/plat/msdos386/build-pkg.lua
new file mode 100644
index 000000000..4b92b5619
--- /dev/null
+++ b/plat/msdos386/build-pkg.lua
@@ -0,0 +1,52 @@
+include("plat/build.lua")
+
+ackfile {
+	name = "boot",
+	srcs = { "./boot.s" },
+	vars = { plat = "msdos386" }
+}
+
+ackfile {
+	name = "stub",
+	srcs = { "./stub.s" },
+	vars = { plat = "msdos386" }
+}
+
+normalrule {
+	name = "stub_aout",
+	ins = {
+		"util/led+led",
+		"+stub"
+	},
+	outleaves = { "stub.aout" },
+	commands = { "%{ins[1]} %{ins[2]} -o %{outs[1]}" }
+}
+
+normalrule {
+	name = "stub_exe",
+	ins = {
+		"util/amisc+aslod",
+		"+stub_aout"
+	},
+	outleaves = { "stub.exe" },
+	commands = { "%{ins[1]} %{ins[2]} %{outs[1]}" }
+}
+
+build_plat_libs {
+	name = "libs",
+	arch = "i386",
+	plat = "msdos386",
+}
+
+installable {
+	name = "pkg",
+	map = {
+		"+tools",
+		"+libs",
+        "./include+pkg",
+		["$(PLATIND)/msdos386/boot.o"] = "+boot",
+		["$(PLATIND)/msdos386/stub.exe"] = "+stub_exe",
+        ["$(PLATIND)/msdos386/libsys.a"] = "./libsys+lib",
+	}
+}
+
diff --git a/plat/msdos386/build-tools.lua b/plat/msdos386/build-tools.lua
new file mode 100644
index 000000000..d28aee904
--- /dev/null
+++ b/plat/msdos386/build-tools.lua
@@ -0,0 +1,21 @@
+include("plat/build.lua")
+
+build_as {
+	name = "as",
+	arch = "i386",
+}
+
+build_ncg {
+	name = "ncg",
+	arch = "i386",
+}
+
+return installable {
+	name = "tools",
+	map = {
+		["$(PLATDEP)/msdos386/as"] = "+as",
+		["$(PLATDEP)/msdos386/ncg"] = "+ncg",
+		["$(PLATIND)/descr/msdos386"] = "./descr",
+		"util/opt+pkg",
+	}
+}
diff --git a/plat/msdos386/descr b/plat/msdos386/descr
new file mode 100644
index 000000000..b6683871b
--- /dev/null
+++ b/plat/msdos386/descr
@@ -0,0 +1,77 @@
+var w=4
+var wa=2
+var p=4
+var pa=2
+var s=2
+var sa=2
+var l=4
+var la=2
+var f=4
+var fa=2
+var d=8
+var da=2
+var x=8
+var xa=2
+var ARCH=i386
+var PLATFORM=msdos386
+var PLATFORMDIR={EM}/share/ack/{PLATFORM}
+var CPP_F=-D__MSDOS__ -D__DOS__ -D_DOS
+var ALIGN=-a0:2 -a1:2 -a2:2 -a3:2
+var MACHOPT_F=-m8
+var EGO_PLAT_FLAGS=-M{EM}/share/ack/ego/{ARCH}.descr
+
+# Override the setting in fe so that files compiled for this platform can see
+# the platform-specific headers.
+
+var C_INCLUDES=-I{PLATFORMDIR}/include -I{EM}/share/ack/include/ansi
+
+name be
+	from .m.g
+	to .s
+	program {EM}/lib/ack/{PLATFORM}/ncg
+	args <
+	stdout
+	need .e
+end
+name as
+	from .s.so
+	to .o
+	program {EM}/lib/ack/{PLATFORM}/as
+	args - -o > <
+	prep cond
+end
+name led
+	from .o.a
+	to .out
+	program {EM}/lib/ack/em_led
+	mapflag -l* LNAME={PLATFORMDIR}/lib*
+	mapflag -fp FLOATS={EM}/{ILIB}fp
+	args {ALIGN} \
+		({RTS}:.b=-u _i_main) \
+	    (.e:{HEAD}={PLATFORMDIR}/boot.o) \
+		({RTS}:.ocm.bas.b={PLATFORMDIR}/c-ansi.o) \
+		({RTS}:.c={PLATFORMDIR}/c-ansi.o) \
+		({RTS}:.mod={PLATFORMDIR}/modula2.o) \
+		({RTS}:.p={PLATFORMDIR}/pascal.o) \
+		-o > < \
+		(.p:{TAIL}={PLATFORMDIR}/libpascal.a) \
+		(.b:{TAIL}={PLATFORMDIR}/libb.a) \
+		(.bas:{TAIL}={PLATFORMDIR}/libbasic.a) \
+		(.mod:{TAIL}={PLATFORMDIR}/libmodula2.a) \
+		(.ocm:{TAIL}={PLATFORMDIR}/liboccam.a) \
+		(.ocm.bas.mod.b.c.p:{TAIL}={PLATFORMDIR}/libc.a) \
+		{FLOATS?} \
+		(.e:{TAIL}={PLATFORMDIR}/libem.a \
+		           {PLATFORMDIR}/libsys.a \
+		           {PLATFORMDIR}/libc.a \
+		           {PLATFORMDIR}/libem.a \
+		           {PLATFORMDIR}/libend.a)
+	linker
+end
+name cv
+	from .out
+	to .exe
+	program {EM}/bin/aslod
+	args -p {PLATFORMDIR}/stub.exe < >
+	outfile msdos386.exe
+end
diff --git a/plat/msdos386/include/ack/plat.h b/plat/msdos386/include/ack/plat.h
new file mode 100644
index 000000000..c0d1b9fff
--- /dev/null
+++ b/plat/msdos386/include/ack/plat.h
@@ -0,0 +1,6 @@
+#ifndef _ACK_PLAT_H
+#define _ACK_PLAT_H
+
+#define ACKCONF_WANT_O_TEXT_O_BINARY 1
+
+#endif
diff --git a/plat/msdos386/include/build.lua b/plat/msdos386/include/build.lua
new file mode 100644
index 000000000..693abd0c1
--- /dev/null
+++ b/plat/msdos386/include/build.lua
@@ -0,0 +1,24 @@
+include("plat/build.lua")
+
+headermap = {}
+packagemap = {}
+
+local function addheader(h)
+	headermap[h] = "./"..h
+	packagemap["$(PLATIND)/msdos386/include/"..h] = "./"..h
+end
+
+addheader("ack/plat.h")
+addheader("sys/types.h")
+
+acklibrary {
+	name = "headers",
+	hdrs = headermap
+}
+
+installable {
+	name = "pkg",
+	map = packagemap
+}
+
+
diff --git a/plat/msdos386/include/sys/types.h b/plat/msdos386/include/sys/types.h
new file mode 100644
index 000000000..005f48eb0
--- /dev/null
+++ b/plat/msdos386/include/sys/types.h
@@ -0,0 +1,9 @@
+#ifndef _SYS_TYPES_H
+#define _SYS_TYPES_H
+
+typedef long pid_t;
+typedef int mode_t;
+typedef long time_t;
+typedef long suseconds_t;
+
+#endif
diff --git a/plat/msdos386/libsys/_hol0.s b/plat/msdos386/libsys/_hol0.s
new file mode 100644
index 000000000..f01566fe8
--- /dev/null
+++ b/plat/msdos386/libsys/_hol0.s
@@ -0,0 +1,19 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .bss
+
+! This data block is used to store information about the current line number
+! and file.
+
+.define hol0
+.comm hol0, 8
diff --git a/plat/msdos386/libsys/brk.s b/plat/msdos386/libsys/brk.s
new file mode 100644
index 000000000..3032bc929
--- /dev/null
+++ b/plat/msdos386/libsys/brk.s
@@ -0,0 +1,18 @@
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+.define _brk
+_brk:
+	mov ebx, esp
+	mov eax, 1*4(ebx)
+	callf (realloc_ptr)
+	xor eax, eax
+	ret
+
+
diff --git a/plat/msdos386/libsys/build.lua b/plat/msdos386/libsys/build.lua
new file mode 100644
index 000000000..71ac521b8
--- /dev/null
+++ b/plat/msdos386/libsys/build.lua
@@ -0,0 +1,35 @@
+acklibrary {
+    name = "lib",
+    srcs = {
+		"./_hol0.s",
+		"./brk.s",
+		"./close.s",
+		"./errno.s",
+		"./getpid.s",
+		"./isatty.s",
+		"./rename.s",
+		"./sbrk.c",
+		"./sys_exists.s",
+		"./sys_getdate.s",
+		"./sys_gettime.s",
+		"./sys_isopen.s",
+		"./sys_isreadyr.s",
+		"./sys_rawcreat.s",
+		"./sys_rawlseek.s",
+		"./sys_rawopen.s",
+		"./sys_rawread.s",
+		"./sys_rawwrite.s",
+		"./sys_xret.s",
+		"./unlink.s",
+		"plat/msdos/libsys+srcs",
+    },
+	deps = {
+		"lang/cem/libcc.ansi/headers+headers",
+		"plat/msdos386/include+headers",
+		"plat/msdos/libsys+headers",
+	},
+    vars = {
+        plat = "msdos386"
+    }
+}
+
diff --git a/plat/msdos386/libsys/close.s b/plat/msdos386/libsys/close.s
new file mode 100644
index 000000000..412307b62
--- /dev/null
+++ b/plat/msdos386/libsys/close.s
@@ -0,0 +1,23 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Close a file.
+
+.define _close
+_close:
+	mov ebx, esp
+	mov ebx, 1*4(esp)
+	movb ah, 0x3E
+	int 0x21
+	jmp .sys_zret
diff --git a/plat/msdos386/libsys/errno.s b/plat/msdos386/libsys/errno.s
new file mode 100644
index 000000000..9858d2640
--- /dev/null
+++ b/plat/msdos386/libsys/errno.s
@@ -0,0 +1,28 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+#define D(e) .define e; e
+
+.sect .data
+
+! Define various ACK error numbers. Note that these are *not* ANSI C
+! errnos, and are used for different purposes.
+
+D(ERANGE)         = 1
+D(ESET)           = 2
+D(EIDIVZ)         = 6
+D(EHEAP)          = 17
+D(EILLINS)        = 18
+D(EODDZ)          = 19
+D(ECASE)          = 20
+D(EBADMON)        = 25
+
diff --git a/plat/msdos386/libsys/getpid.s b/plat/msdos386/libsys/getpid.s
new file mode 100644
index 000000000..d2a250491
--- /dev/null
+++ b/plat/msdos386/libsys/getpid.s
@@ -0,0 +1,45 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Copyright (c) 2021--2022 TK Chia
+!
+! The authors hereby grant permission to use, copy, modify, distribute,
+! and license this software and its documentation for any purpose, provided
+! that existing copyright notices are retained in all copies and that this
+! notice is included verbatim in any distributions. No written agreement,
+! license, or royalty fee is required for any of the authorized uses.
+! Modifications to this software may be copyrighted by their authors
+! and need not follow the licensing terms described here, provided that
+! the new terms are clearly indicated on the first page of each file where
+! they apply.
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Get the current process identifier.  For MS-DOS, use the Program Segment
+! Prefix (PSP) segment as the PID, unless the system supports an actual
+! `getpid' syscall, e.g. European MS-DOS 4.0.
+!
+! (Note that pid_t is a 32-bit type.  This is to allow for PSP segments and
+! MS-DOS PIDs above 0x7FFF.)
+
+.define _getpid
+_getpid:
+	movb ah, 0x87
+	stc
+	int 0x21
+	jnc .eur_dos
+	movb ah, 0x51
+	int 0x21
+	xchg ebx, eax
+.eur_dos:
+	xor edx, edx
+	ret
diff --git a/plat/msdos386/libsys/isatty.s b/plat/msdos386/libsys/isatty.s
new file mode 100644
index 000000000..794274bfa
--- /dev/null
+++ b/plat/msdos386/libsys/isatty.s
@@ -0,0 +1,37 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Say whether a given file descriptor number refers to a terminal.
+
+.define _isatty
+_isatty:
+	mov ebx, esp
+	mov ebx, 4(ebx)
+	o16 mov ax, 0x4400
+	int 0x21
+	jc error
+	testb dl, dl
+	jz not_tty
+	mov eax, 1
+	ret
+not_tty:
+	mov (_errno), 25		! ENOTTY
+not_tty_2:
+	xor eax, eax
+	ret
+error:
+	push eax
+	call __sys_seterrno
+	pop ecx
+	jmp not_tty_2
diff --git a/plat/msdos386/libsys/rename.s b/plat/msdos386/libsys/rename.s
new file mode 100644
index 000000000..4b43a0d48
--- /dev/null
+++ b/plat/msdos386/libsys/rename.s
@@ -0,0 +1,54 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Rename a file.
+
+.define _rename
+_rename:
+	mov ebx, esp
+	push esi
+	push edi
+
+	! Source filename.
+
+	mov esi, 4(ebx)
+    movzx edi, (transfer_buffer_ptr)
+    mov es, (pmode_ds)
+    cld
+1:
+	lodsb
+	stosb
+	testb al, al
+	jnz 1b
+	
+	! Destination filename.
+
+	mov eax, edi
+	mov esi, 8(ebx)
+1:
+	lodsb
+	stosb
+	testb al, al
+	jnz 1b
+	
+	! Make the DOS call.
+
+	o16 mov dx, (transfer_buffer_ptr)
+	o16 mov di, ax
+	movb ah, 0x56
+	or ebx, 0x210000
+	callf (interrupt_ptr)
+	pop edi
+	pop esi
+	jmp .sys_zret
diff --git a/plat/msdos386/libsys/sbrk.c b/plat/msdos386/libsys/sbrk.c
new file mode 100644
index 000000000..2dbd610f3
--- /dev/null
+++ b/plat/msdos386/libsys/sbrk.c
@@ -0,0 +1,40 @@
+/* $Source$
+ * $State$
+ * $Revision$
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include "libsys.h"
+
+extern char _end[1];
+static char* current = _end;
+
+void* sbrk(int increment)
+{
+	char* old;
+	char* new;
+
+	if (increment == 0)
+		return current;
+		
+	old = current;
+
+	new = old + increment;
+
+	if ((increment > 0) && (new <= old))
+		goto out_of_memory;
+	else if ((increment < 0) && (new >= old))
+		goto out_of_memory;
+
+	if (brk(new) < 0)
+		goto out_of_memory;
+		
+	current = new;
+	return old;
+
+out_of_memory:
+	errno = ENOMEM;
+	return OUT_OF_MEMORY;
+}
diff --git a/plat/msdos386/libsys/sys_exists.s b/plat/msdos386/libsys/sys_exists.s
new file mode 100644
index 000000000..f57d28b3e
--- /dev/null
+++ b/plat/msdos386/libsys/sys_exists.s
@@ -0,0 +1,25 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Say whether a file exists with the given name.
+
+.define __sys_exists
+__sys_exists:
+	mov ebx, esp
+	mov edx, 4(ebx)
+	mov eax, 0x4300
+	int 0x21
+	sbb eax, eax
+	inc eax
+	ret
diff --git a/plat/msdos386/libsys/sys_getdate.s b/plat/msdos386/libsys/sys_getdate.s
new file mode 100644
index 000000000..981253b93
--- /dev/null
+++ b/plat/msdos386/libsys/sys_getdate.s
@@ -0,0 +1,25 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Get the current system date from MS-DOS.
+
+.define __sys_getdate
+__sys_getdate:
+	movb ah, 0x2a
+	int 0x21
+	mov ebx, esp
+	mov ebx, 4(ebx)
+	o16 mov 0(ebx), dx
+	o16 mov 2(ebx), cx
+	ret
diff --git a/plat/msdos386/libsys/sys_gettime.s b/plat/msdos386/libsys/sys_gettime.s
new file mode 100644
index 000000000..733ad58ac
--- /dev/null
+++ b/plat/msdos386/libsys/sys_gettime.s
@@ -0,0 +1,26 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Get the current system time from MS-DOS.
+
+.define __sys_gettime
+__sys_gettime:
+	int 3
+	movb ah, 0x2c
+	int 0x21
+	mov ebx, esp
+	mov ebx, 4(ebx)
+	o16 mov 0(ebx), cx
+	o16 mov 2(ebx), dx
+	ret
diff --git a/plat/msdos386/libsys/sys_isopen.s b/plat/msdos386/libsys/sys_isopen.s
new file mode 100644
index 000000000..5a5fed07c
--- /dev/null
+++ b/plat/msdos386/libsys/sys_isopen.s
@@ -0,0 +1,26 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Say whether a given file descriptor number refers to a valid open file
+! descriptor.
+
+.define __sys_isopen
+__sys_isopen:
+	mov ebx, esp
+	mov ebx, 4(bx)
+	mov eax, 0x4400
+	int 0x21
+	sbb eax, eax
+	inc eax
+	ret
diff --git a/plat/msdos386/libsys/sys_isreadyr.s b/plat/msdos386/libsys/sys_isreadyr.s
new file mode 100644
index 000000000..9a646adc8
--- /dev/null
+++ b/plat/msdos386/libsys/sys_isreadyr.s
@@ -0,0 +1,29 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Say whether a file descriptor is ready for input, i.e. reading from the
+! fd will immediately return something.
+
+.define __sys_isreadyr
+__sys_isreadyr:
+	mov ebx, esp
+	mov eax, 0x4406
+	mov ebx, 4(ebx)
+	int 0x21
+	jnc ok
+	movb al, 0
+ok:
+	o16 cbw
+	cwde
+	ret
diff --git a/plat/msdos386/libsys/sys_rawcreat.s b/plat/msdos386/libsys/sys_rawcreat.s
new file mode 100644
index 000000000..b15df3f4f
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawcreat.s
@@ -0,0 +1,45 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Create or truncate a file.
+
+.define __sys_rawcreat
+__sys_rawcreat:
+	! Copy filename to transfer buffer.
+
+	mov ebx, esp
+	push esi
+	push edi
+	mov esi, 4(ebx)
+    movzx edi, (transfer_buffer_ptr)
+    mov es, (pmode_ds)
+    cld
+1:
+	lodsb
+	stosb
+	testb al, al
+	jnz 1b
+
+	! Make the DOS call.
+
+	movb ah, 0x3c
+	movzx edx, (transfer_buffer_ptr)
+	movb al, 8(ebx)
+	or ebx, 0x210000
+	callf (interrupt_ptr)
+
+	pop edi
+	pop esi
+	jmp .sys_axret
+
diff --git a/plat/msdos386/libsys/sys_rawlseek.s b/plat/msdos386/libsys/sys_rawlseek.s
new file mode 100644
index 000000000..c38a1e0b1
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawlseek.s
@@ -0,0 +1,26 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Move the current file position for a file descriptor.
+
+.define __sys_rawlseek
+__sys_rawlseek:
+	movb ah, 0x42
+	mov ebx, esp
+	mov edx, 8(bx)
+	mov ecx, 12(bx)
+	movb al, 16(bx)
+	mov ebx, 4(bx)
+	int 0x21
+	jmp .sys_dxaxret
diff --git a/plat/msdos386/libsys/sys_rawopen.s b/plat/msdos386/libsys/sys_rawopen.s
new file mode 100644
index 000000000..bb4ff5acb
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawopen.s
@@ -0,0 +1,45 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Open an existing file.
+
+.define __sys_rawopen
+__sys_rawopen:
+	! Copy filename to transfer buffer.
+
+	mov ebx, esp
+	push esi
+	push edi
+
+	mov esi, 4(ebx)
+    movzx edi, (transfer_buffer_ptr)
+    mov es, (pmode_ds)
+    cld
+1:
+	lodsb
+	stosb
+	testb al, al
+	jnz 1b
+
+	! Make the DOS call.
+
+	movb ah, 0x3d
+	o16 mov dx, (transfer_buffer_ptr)
+	movb al, 8(ebx)
+	or ebx, 0x210000
+	callf (interrupt_ptr)
+
+	pop edi
+	pop esi
+	jmp .sys_axret
diff --git a/plat/msdos386/libsys/sys_rawread.s b/plat/msdos386/libsys/sys_rawread.s
new file mode 100644
index 000000000..f5b0c1a35
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawread.s
@@ -0,0 +1,74 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Read bytes from a file descriptor.  These routines do not do any
+! translation between CRLF and LF line endings.
+!
+! Note that, for MS-DOS, a raw "write" request of zero bytes will truncate
+! (or extend) the file to the current file position.
+
+.define __sys_rawread
+__sys_rawread:
+	enter 0, 0
+	push esi
+	push edi
+file_handle = 2*4
+write_buffer = 3*4
+amount_to_read = 4*4
+
+	mov eax, amount_to_read(ebp)
+	mov ecx, 32*1024
+	cmp eax, ecx
+	jge 2f
+	mov ecx, eax
+2:
+
+	! Read from DOS into the transfer buffer.
+
+	movb ah, 0x3f
+	o16 mov dx, (transfer_buffer_ptr)
+	o16 mov bx, file_handle(ebp)
+	or ebx, 0x210000
+	callf (interrupt_ptr)
+	jnc success
+
+	! Process errors.
+
+	push eax
+	call __sys_seterrno
+	pop ecx
+	jmp exit
+success:
+
+	! Copy eax bytes out of the transfer buffer.
+
+	push eax
+	mov ecx, eax
+	movzx esi, (transfer_buffer_ptr)
+	mov edi, write_buffer(ebp)
+	mov es, (pmode_ds)
+	cld
+1:
+	eseg lodsb
+	movb (edi), al
+	inc edi
+	loop 1b
+	pop eax
+
+exit:
+	pop edi
+	pop esi
+	leave
+	ret
+
diff --git a/plat/msdos386/libsys/sys_rawwrite.s b/plat/msdos386/libsys/sys_rawwrite.s
new file mode 100644
index 000000000..3ac3a7e16
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawwrite.s
@@ -0,0 +1,66 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Write bytes to/to a file descriptor.  These routines do not do any
+! translation between CRLF and LF line endings.
+!
+! Note that, for MS-DOS, a raw "write" request of zero bytes will truncate
+! (or extend) the file to the current file position.
+
+.define __sys_rawwrite
+__sys_rawwrite:
+    enter 0, 0
+    push esi
+    push edi
+file_handle = 2*4
+read_buffer = 3*4
+amount_to_write = 4*4
+
+    mov eax, amount_to_write(ebp)
+    mov ecx, 32*1024        ! size of transfer buffer
+    cmp eax, ecx
+    jge 2f
+    mov ecx, eax
+2:
+
+    ! Copy ecx bytes into the transfer buffer.
+
+    push ecx
+    mov esi, read_buffer(ebp)
+    movzx edi, (transfer_buffer_ptr)
+    mov es, (pmode_ds)
+    cld
+    rep movsb
+    pop ecx
+
+    ! Write from the transfer buffer to DOS.
+
+    movb ah, 0x40
+    o16 mov dx, (transfer_buffer_ptr)
+    o16 mov bx, file_handle(ebp)
+    or ebx, 0x210000
+    callf (interrupt_ptr)
+    jnc exit
+
+    push eax
+    call __sys_seterrno
+    pop ecx
+exit:
+    pop edi
+    pop esi
+    leave
+    ret
+
+! vim: sw=4 ts=4 et
+
diff --git a/plat/msdos386/libsys/sys_xret.s b/plat/msdos386/libsys/sys_xret.s
new file mode 100644
index 000000000..20c2b454b
--- /dev/null
+++ b/plat/msdos386/libsys/sys_xret.s
@@ -0,0 +1,50 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! .sys_zret: if the carry flag is set, then set `errno' from the DOS error
+! code in ax, and return an int -1.  If the carry flag is clear, just
+! return an int zero.
+!
+! .sys_axret: if the carry flag is set, then set `errno' from the DOS error
+! code in ax, and return a shortword -1.  If the carry flag is clear, just
+! return ax as a return value.
+!
+! .sys_dxaxret: same as .sys_axret, but return -1 or dx:ax as a return value.
+
+.extern .sys_zret
+.extern .sys_axret
+.extern .sys_dxaxret
+.sys_zret:
+	jc error
+	xor eax, eax
+no_error:
+	ret
+
+.sys_axret:
+	jc error
+	ret
+
+.sys_dxaxret:
+	jc error
+	shl edx, 16
+	o16 mov dx, ax
+	mov eax, edx
+	ret
+
+error:
+	movzx eax, ax
+	push eax
+	call __sys_seterrno
+	pop ecx
+	ret
diff --git a/plat/msdos386/libsys/unlink.s b/plat/msdos386/libsys/unlink.s
new file mode 100644
index 000000000..7d023ad48
--- /dev/null
+++ b/plat/msdos386/libsys/unlink.s
@@ -0,0 +1,44 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Remove a file.
+
+.define _unlink
+_unlink:
+	! Copy filename to transfer buffer.
+
+	mov ebx, esp
+	push esi
+	push edi
+
+	mov esi, 4(ebx)
+    movzx edi, (transfer_buffer_ptr)
+    mov es, (pmode_ds)
+    cld
+1:
+	lodsb
+	stosb
+	testb al, al
+	jnz 1b
+
+	! Make the DOS call.
+
+    movzx edi, (transfer_buffer_ptr)
+	movb ah, 0x41
+	or ebx, 0x210000
+	callf (interrupt_ptr)
+
+	pop edi
+	pop esi
+	jmp .sys_zret
diff --git a/plat/msdos386/stub.s b/plat/msdos386/stub.s
new file mode 100644
index 000000000..219d66470
--- /dev/null
+++ b/plat/msdos386/stub.s
@@ -0,0 +1,410 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+.use16
+exe_header:
+    .data2 0x5a4d               ! magic number
+    .data2 exe_last_page        ! number of bytes in last loadable page
+    .data2 exe_text_pages       ! size of .exe, in pages
+    .data2 0                    ! number of relocation entries
+    .data2 0                    ! start of loadable area, in 16-byte paragraphs
+    .data2 exe_ram_paras        ! required RAM size, in 16-byte paragraphs
+    .data2 exe_ram_paras        ! maximum RAM siz, in 16-byte paragraphs
+    .data2 0                    ! initial SS, relative to program
+    .data2 stack                ! initial SP
+    .data2 0                    ! checksum (ignored)
+    .data2 exe_start            ! initial IP
+    .data2 0                    ! initial CS, relative to program
+    .data2 0                    ! offset of relocation table
+    .data2 0                    ! overlay number
+
+exe_start:
+    ! On entry, DS=ES=PSP. Make DS=CS, so we're running in tiny mode.
+
+    push cs
+    pop ds
+    mov (rseg), ds
+    mov (pspseg), es
+
+    ! Ensure that at least two handles are available by blindly closing some.
+
+	mov	bx, 19                  ! close handle
+	movb ah, 0x3e
+	int	0x21
+	mov	bx, 18                  ! close handle
+	movb ah, 0x3e
+	int	0x21
+     
+    ! Scan the environment to find the program name.
+
+    eseg mov es, (0x2c)         ! environment pointer segment from PSP
+    xor di, di
+    xorb al, al
+    mov cx, 0xffff
+    cld
+1:
+    repne scasb                 ! find end of next string
+    eseg cmpb (di), 0
+    jnz 1b
+2:
+    add di, 3
+    mov si, di
+    repne scasb
+
+    ! es:si now points at the program name, and es:di at one past the end.
+
+    mov cx, di
+    sub cx, si
+    sub sp, cx                  ! allocate space on stack
+    mov di, sp                  ! es:si source, ds:di dest
+1:
+    eseg movb al, (si)
+    inc si
+    movb (di), al
+    inc di
+    cmpb al, 0
+    jnz 1b
+
+    ! Open the file. (0x5f)
+
+    mov dx, sp
+    mov ax, 0x3d00
+    int 0x21
+    jc no_file
+    mov (fh), ax
+    add sp, cx                  ! don't need filename any more
+
+    ! Get the file length (== text len).
+
+    mov bx, ax
+    mov ax, 0x4202
+    xor cx, cx                  ! high offset
+    xor dx, dx                  ! low offset
+    int 0x21                    ! lseek
+    mov (pmemlen+0), ax
+    mov (pmemlen+2), dx
+
+    ! Initialise DPMI.
+
+    mov ax, 0x1687
+    int 0x2f
+    or ax, ax
+    jnz no_dpmi
+    mov (pmode_switch+0), di    ! write back PMODE switch routine
+    mov (pmode_switch+2), es
+    or si, si                   ! do we need a DPMI private area?
+    jz 1f
+
+    mov bx, si
+    movb ah, 0x48
+    int 0x21                    ! allocate memory from DOS
+    mov es, ax                  ! data area segment -> es
+1:
+    ! Switch to protected mode.
+
+    mov ax, 1                   ! 32-bit app
+    callf (pmode_switch)
+    jc bad_dpmi
+
+    ! We're now in protected mode.
+
+    mov (psegcs), cs
+    mov (psegds), ds
+
+    ! Allocate space for the code segment.
+
+    mov ax, 0x0000
+    mov cx, 1
+    int 0x31                    ! allocate LDT
+    jc bad_dpmi
+    mov es, ax
+    mov (psegcs32), ax
+
+    mov cx, (pmemlen+0)
+    mov bx, (pmemlen+2)
+    mov ax, 0x0501
+    int 0x31                    ! allocate linear address
+    jc bad_dpmi
+    mov (pmemhandle+0), di
+    mov (pmemhandle+2), si
+
+    mov dx, cx
+    mov cx, bx
+    mov bx, es
+    mov ax, 0x0007
+    int 0x31                    ! set segment base address
+    jc bad_dpmi
+
+    mov bx, es
+    mov dx, (pmemlen+0)
+    mov cx, (pmemlen+2)
+    mov ax, 0x0008
+    int 0x31                    ! set segment limit
+
+    mov cx, cs
+    and cx, 3
+    shl cx, 5
+    or cx, 0xc09b               ! 32-bit, big, code, non-conforming, readable
+    mov bx, es
+    mov ax, 0x0009
+    int 0x31                    ! set descriptor access rights
+
+    ! Allocate the data segment (as a simple clone of the code segment). (10e)
+
+    mov ax, 0x000a
+    mov bx, es
+    int 0x31
+    mov fs, ax
+    mov (psegds32), ax
+
+    mov cx, ax
+    and cx, 3
+    shl cx, 5
+    or cx, 0xc093               ! 32-bit, big, data, r/w, expand-up
+    mov bx, fs
+    mov ax, 0x0009
+    int 0x31                    ! set descriptor access rights
+
+    ! Load the program.
+
+    mov bx, (fh)
+    mov ax, 0x4200
+    xor cx, cx                  ! high offset
+    mov dx, text_top            ! low offset
+    int 0x21                    ! lseek
+
+    o32 xor edi, edi            ! destination 32-bit register
+1:
+    movb ah, 0x3f
+    mov bx, (fh)
+    mov cx, TRANSFER_BUFFER_SIZE
+    mov dx, transfer_buffer
+    o32 push edi
+    call int21                  ! read up to 32kB into transfer buffer
+    o32 pop edi
+    cmp ax, 0
+    je 2f
+
+    o32 movzx ecx, ax           ! number of bytes read
+    o32 mov esi, transfer_buffer
+    cld
+    o32 rep movsb
+    jmp 1b
+2:
+
+    ! Close the file.
+
+    movb ah, 0x3e
+    mov bx, (fh)
+    int 0x21                    ! close
+
+    ! Jump to the new segment and enter 32-bit mode!
+
+    o32 movzx eax, (psegcs)
+    o32 movzx ebx, (psegds)
+    o32 movzx ecx, (rseg)
+    o32 mov edx, realloc
+    o32 mov esi, interruptf
+    o32 mov edi, transfer_buffer
+    push es
+    pop ds
+    push es
+    push 0
+    retf ! 19b
+
+    ! Helper routine which reallocates the linear block that the 32-bit code
+    ! is running from. This can't happen from inside the 32-bit code itself
+    ! because it might move.
+    !
+    ! On entry, ds and ss are ignored. On exit, ds is set to the 32-bit segment.
+    !  eax: new block size
+realloc:
+    cseg mov ds, (psegds)
+    cli                         ! atomically switch stacks
+    o32 mov (dpmi_ebp), esp     ! yes, saving esp into the ebp field
+    mov (dpmi_ss), ss
+    mov ss, (psegds)
+    mov sp, dosstack
+    sti
+    pusha
+
+    o32 add eax, 1024*1024 - 1
+    o32 and eax, ~[1024*1024 - 1]
+    o32 mov (pmemlen), eax
+    mov cx, (pmemlen+0)
+    mov bx, (pmemlen+2)
+    mov di, (pmemhandle+0)
+    mov si, (pmemhandle+2)
+    mov ax, 0x0503
+    int 0x31                    ! resize memory block
+    jc bad_dpmi
+    mov (pmemhandle+0), di
+    mov (pmemhandle+2), si
+    mov (pmemaddr+0), cx
+    mov (pmemaddr+2), bx
+
+    mov bx, (psegds32)
+    mov dx, (pmemlen+0)
+    mov cx, (pmemlen+2)
+    mov ax, 0x0008
+    int 0x31                    ! set ds segment limit
+    jc bad_dpmi
+    mov dx, (pmemaddr+0)
+    mov cx, (pmemaddr+2)
+    mov ax, 0x0007
+    int 0x31                    ! set ds linear address
+    jc bad_dpmi
+    mov bx, (psegcs32)
+    int 0x31                    ! set cs linear address
+    jc bad_dpmi
+    
+    popa
+    o32 mov eax, (pmemlen)
+    cli                         ! atomically switch stacks back
+    mov ss, (dpmi_ss)
+    o32 mov esp, (dpmi_ebp)
+    mov ds, (psegds32)
+    sti
+
+    o32 retf
+
+bad_dpmi:
+    mov si, bad_dpmi_msg
+    jmp exit_with_error
+
+no_file:
+    mov si, no_file_msg
+    jmp exit_with_error
+
+no_dpmi:
+    mov si, no_dpmi_msg
+    ! fall through
+
+! Displays the message in si and exits.
+! This uses a loop because from protected mode any interrupt which
+! takes a pointer parameter requires special treatment.
+exit_with_error:
+    movb dl, (si)
+    cmpb dl, 0
+    je 1f
+    inc si
+
+    movb ah, 2
+    int 0x21                    ! print character
+    jmp exit_with_error
+1:
+    mov ax, 0x4cff
+    int 0x21                    ! terminate with error code al
+
+    ! Simulate DOS interrupt.
+int21:
+    o32 or ebx, 0x210000
+    ! Simulate interrupt in the high half of ebx.
+interrupt:
+    mov (dpmi_eax), ax
+    mov (dpmi_ebx), bx
+    mov (dpmi_ecx), cx
+    mov (dpmi_edx), dx
+    mov (dpmi_esi), si
+    mov (dpmi_edi), di
+    mov ax, (rseg)
+    mov (dpmi_ds), ax
+    mov (dpmi_ss), ax
+    push es
+    mov (dpmi_sp), dosstack     ! auto stack is too small
+    push ds
+    pop es
+    o32 mov edi, dpmi_edi
+    mov ax, 0x300
+    o32 shr ebx, 16
+    int 0x31                    ! simulate DOS interrupt
+    pop es
+    o32 movzx eax, (dpmi_eax)
+    o32 movzx ebx, (dpmi_ebx)
+    o32 movzx ecx, (dpmi_ecx)
+    o32 movzx edx, (dpmi_edx)
+    o32 movzx esi, (dpmi_esi)
+    o32 movzx edi, (dpmi_edi)
+    push (dpmi_flags)
+    popf
+    ret
+
+! Far call wrapper around interrupt.
+interruptf:
+    push ds
+    cseg mov ds, (psegds)
+    call interrupt
+    pop ds
+    o32 retf
+
+bad_dpmi_msg:
+    .asciz "DPMI error during setup"
+no_file_msg:
+    .asciz "Couldn't open .exe"
+no_dpmi_msg:
+    .asciz "No DPMI host installed"
+.align 4
+text_top:
+
+exe_text_pages = [text_top - exe_header + 511] / 512
+exe_last_page = [text_top - exe_header] % 512
+
+.sect .rom
+
+.sect .bss
+bss_start:
+
+dpmi_edi:       .space 4
+dpmi_esi:       .space 4
+dpmi_ebp:       .space 4
+                .space 4 ! reserved
+dpmi_ebx:       .space 4
+dpmi_edx:       .space 4
+dpmi_ecx:       .space 4
+dpmi_eax:       .space 4
+dpmi_flags:     .space 2
+dpmi_es:        .space 2
+dpmi_ds:        .space 2
+dpmi_fs:        .space 2
+dpmi_gs:        .space 2
+dpmi_ip:        .space 2
+dpmi_cs:        .space 2
+dpmi_sp:        .space 2
+dpmi_ss:        .space 2
+
+pmode_switch:   .space 4
+rseg:           .space 2 ! real mode
+pspseg:         .space 2 ! real mode
+psegcs:         .space 2 ! protected mode 16-bit code segment
+psegds:         .space 2 ! protected mode 16-bit data segment
+psegcs32:       .space 2 ! protected mode 32-bit code segment
+psegds32:       .space 2 ! protected mode 32-bit data segment
+pmemaddr:       .space 4 ! protected mode linear memory address
+pmemhandle:     .space 4 ! protected mode linear memory handle
+pmemlen:        .space 4 ! protected mode linear memory length
+fh:             .space 2
+
+    .space 512
+stack:
+    .space 512
+dosstack:
+
+TRANSFER_BUFFER_SIZE = 32*1024
+transfer_buffer:
+    .space TRANSFER_BUFFER_SIZE
+
+bss_top:
+exe_ram_paras = [bss_top - bss_start + 15] / 16
+
+! vim: ts=4 sw=4 et ft=asm
+
diff --git a/plat/msdos86/descr b/plat/msdos86/descr
index 333bb671b..2ef1724ee 100644
--- a/plat/msdos86/descr
+++ b/plat/msdos86/descr
@@ -84,5 +84,5 @@ name cv
 	mapflag -i LOD=amzlod
 	program {EM}/bin/{LOD}
 	args < >
-	outfile msdos86.exe
+	outfile msdos86.com
 end
diff --git a/plat/msdos86/libsys/build.lua b/plat/msdos86/libsys/build.lua
index e39d90837..96988002d 100644
--- a/plat/msdos86/libsys/build.lua
+++ b/plat/msdos86/libsys/build.lua
@@ -3,42 +3,28 @@ acklibrary {
     srcs = {
 		"./brk.c",
 		"./close.s",
-		"./creat.c",
 		"./errno.s",
 		"./getpid.s",
-		"./gettimeofday.c",
 		"./_hol0.s",
 		"./isatty.s",
-		"./kill.c",
-		"./lseek.c",
-		"./open.c",
-		"./read.c",
 		"./rename.s",
-		"./setmode.c",
-		"./signal.c",
 		"./sys_exists.s",
-		"./sys_fdmodes.c",
 		"./sys_getdate.s",
-		"./sys_getmode.c",
 		"./sys_gettime.s",
-		"./sys_initmain.c",
-		"./sys_iseof.c",
 		"./sys_isopen.s",
 		"./sys_isreadyr.s",
 		"./sys_rawcreat.s",
 		"./sys_rawlseek.s",
 		"./sys_rawopen.s",
 		"./sys_rawrw.s",
-		"./sys_seteof.c",
-		"./sys_seterrno.c",
-		"./sys_setmode.c",
 		"./sys_xret.s",
 		"./unlink.s",
-		"./write.c",
+		"plat/msdos/libsys+srcs",
     },
 	deps = {
 		"lang/cem/libcc.ansi/headers+headers",
 		"plat/msdos86/include+headers",
+		"plat/msdos/libsys+headers",
 	},
     vars = {
         plat = "msdos86"
diff --git a/plat/msdos86/libsys/write.c b/plat/msdos86/libsys/write.c
deleted file mode 100644
index fc744b256..000000000
--- a/plat/msdos86/libsys/write.c
+++ /dev/null
@@ -1,61 +0,0 @@
-/* $Source$
- * $State$
- * $Revision$
- */
-
-#include <stdlib.h>
-#include <string.h>
-#include <errno.h>
-#include <unistd.h>
-#include "libsys.h"
-
-ssize_t write(int fd, void* buffer, size_t count)
-{
-	static const char crlf[2] = "\r\n";
-	int i;
-	char *p, *q;
-	size_t left, n;
-	ssize_t r, tot;
-
-	if (!count)
-		return 0;
-
-	if (_sys_getmode(fd) == O_BINARY)
-		return _sys_rawwrite(fd, buffer, count);
-
-	/* If the file descriptor is an O_TEXT fd, translate LFs to CRLFs. */
-	p = buffer;
-	left = count;
-	tot = 0;
-	while (left)
-	{
-		q = memchr(p, '\n', left);
-		if (!q)
-			return _sys_rawwrite(fd, p, left);
-
-		n = q - p;
-		if (n)
-		{
-			r = _sys_rawwrite(fd, p, n);
-			if (r <= 0)
-				return tot ? tot : r;
-			tot += r;
-			p += r;
-			left -= r;
-			if (r != n)
-				break;
-		}
-
-		r = _sys_rawwrite(fd, crlf, sizeof crlf);
-		if (r != 2)
-		{
-			if (r > 0)
-				r = 0;
-			return tot ? tot : r;
-		}
-		++tot;
-		++p;
-		--left;
-	}
-	return tot;
-}
diff --git a/util/amisc/aslod.1 b/util/amisc/aslod.1
index 5a1f857a0..a9f15ef3a 100644
--- a/util/amisc/aslod.1
+++ b/util/amisc/aslod.1
@@ -3,7 +3,7 @@
 aslod \- ACK simple loader
 .SH SYNOPSIS
 .B aslod
-[\-h] [\-v] inputfile outputfile
+[\-h] [\-v] [\-p prefixfile] inputfile outputfile
 .SH DESCRIPTION
 .I aslod
 converts an absolute ack.out file into a simple binary memory dump.
@@ -16,5 +16,8 @@ The file must have all references resolved and be linked to a
 fixed address. aslod will dump the segments, in order, such
 that the first byte of TEXT is at offset 0 in the file
 (regardless of where it is in memory).
+.PP
+If a prefix file is specified, this is prepended to the output before writing.
+No changes to the output itself are made.
 .SH "SEE ALSO"
 ack.out(5)
diff --git a/util/amisc/aslod.c b/util/amisc/aslod.c
index 850c805f1..d5c3bee53 100644
--- a/util/amisc/aslod.c
+++ b/util/amisc/aslod.c
@@ -37,6 +37,7 @@ struct outsect outsect[S_MAX];
 char* stringarea;
 
 char* outputfile = NULL;                /* Name of output file, or NULL */
+char* prefixfile = NULL;				/* Name of prefix file, or NULL */
 char* program;                          /* Name of current program: argv[0] */
 
 FILE* input;                            /* Input stream */
@@ -136,6 +137,19 @@ void emits(struct outsect* section, struct outsect* nextsect)
 	}
 }
 
+void emitprefixfile(void)
+{
+	FILE* fp = fopen(prefixfile, "rb");
+
+	while (!feof(fp))
+	{
+		char buffer[BUFSIZ];
+		size_t blocksize = fread(buffer, 1, BUFSIZ, fp);
+		writef(buffer, 1, blocksize);
+	}
+
+	fclose(fp);
+}
 
 /* Macros from modules/src/object/obj.h */
 #define Xchar(ch)	((ch) & 0377)
@@ -204,6 +218,12 @@ int main(int argc, char* argv[])
 				verbose = true;
 				break;
 
+			case 'p':
+				argv++;
+				argc--;
+				prefixfile = argv[1];
+				break;
+
 			default:
 			syntaxerror:
 				fatal("syntax error --- try -h for help");
@@ -288,6 +308,8 @@ int main(int argc, char* argv[])
 
 	/* And go! */
 	
+	if (prefixfile)
+		emitprefixfile();
 	emits(&outsect[TEXT], &outsect[ROM]);
 	emits(&outsect[ROM], &outsect[DATA]);
 	emits(&outsect[DATA], NULL);