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/msdos/libsys/brk.c b/plat/msdos386/libsys/brk.c
similarity index 100%
rename from plat/msdos/libsys/brk.c
rename to plat/msdos386/libsys/brk.c
diff --git a/plat/msdos386/libsys/build.lua b/plat/msdos386/libsys/build.lua
index 2725c0f70..70c7eaa17 100644
--- a/plat/msdos386/libsys/build.lua
+++ b/plat/msdos386/libsys/build.lua
@@ -1,39 +1,24 @@
 acklibrary {
     name = "lib",
     srcs = {
+		"./brk.c",
+		"./close.s",
+		"./errno.s",
+		"./getpid.s",
+		"./_hol0.s",
+		"./isatty.s",
 		"./rename.s",
---		"./brk.c",
---		"./close.s",
---		"./creat.c",
---		"./errno.s",
---		"./getpid.s",
---		"./gettimeofday.c",
---		"./_hol0.s",
---		"./isatty.s",
---		"./kill.c",
---		"./lseek.c",
---		"./open.c",
---		"./read.c",
---		"./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",
+		"./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_rawrw.s",
+		"./sys_xret.s",
+		"./unlink.s",
 		"plat/msdos/libsys+srcs",
     },
 	deps = {
diff --git a/plat/msdos386/libsys/close.s b/plat/msdos386/libsys/close.s
new file mode 100644
index 000000000..b8c2f8a15
--- /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 bx, sp
+	mov bx, 2(bx)
+	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..5aa80638b
--- /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 bx, ax
+.eur_dos:
+	xor dx, dx
+	ret
diff --git a/plat/msdos386/libsys/isatty.s b/plat/msdos386/libsys/isatty.s
new file mode 100644
index 000000000..bd2e195e6
--- /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 bx, sp
+	mov bx, 2(bx)
+	mov ax, 0x4400
+	int 0x21
+	jc error
+	testb dl, dl
+	jz not_tty
+	mov ax, 1
+	ret
+not_tty:
+	mov (_errno), 25		! ENOTTY
+not_tty_2:
+	xor ax, ax
+	ret
+error:
+	push ax
+	call __sys_seterrno
+	pop cx
+	jmp not_tty_2
diff --git a/plat/msdos386/libsys/rename.s b/plat/msdos386/libsys/rename.s
new file mode 100644
index 000000000..edb14266b
--- /dev/null
+++ b/plat/msdos386/libsys/rename.s
@@ -0,0 +1,26 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Rename a file.
+
+.define _rename
+_rename:
+	mov bx, sp
+	push di
+	mov dx, 2(bx)
+	mov di, 4(bx)
+	movb ah, 0x56
+	int 0x21
+	pop di
+	jmp .sys_zret
diff --git a/plat/msdos386/libsys/sys_exists.s b/plat/msdos386/libsys/sys_exists.s
new file mode 100644
index 000000000..e282ef687
--- /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 bx, sp
+	mov dx, 2(bx)
+	mov ax, 0x4300
+	int 0x21
+	sbb ax, ax
+	inc ax
+	ret
diff --git a/plat/msdos386/libsys/sys_getdate.s b/plat/msdos386/libsys/sys_getdate.s
new file mode 100644
index 000000000..41d69fc85
--- /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 bx, sp
+	mov bx, 2(bx)
+	mov (bx), dx
+	mov 2(bx), cx
+	ret
diff --git a/plat/msdos386/libsys/sys_gettime.s b/plat/msdos386/libsys/sys_gettime.s
new file mode 100644
index 000000000..d062fad8d
--- /dev/null
+++ b/plat/msdos386/libsys/sys_gettime.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 time from MS-DOS.
+
+.define __sys_gettime
+__sys_gettime:
+	movb ah, 0x2c
+	int 0x21
+	mov bx, sp
+	mov bx, 2(bx)
+	mov (bx), cx
+	mov 2(bx), dx
+	ret
diff --git a/plat/msdos386/libsys/sys_isopen.s b/plat/msdos386/libsys/sys_isopen.s
new file mode 100644
index 000000000..5ce49ed45
--- /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 bx, sp
+	mov bx, 2(bx)
+	mov ax, 0x4400
+	int 0x21
+	sbb ax, ax
+	inc ax
+	ret
diff --git a/plat/msdos386/libsys/sys_isreadyr.s b/plat/msdos386/libsys/sys_isreadyr.s
new file mode 100644
index 000000000..b5d0800ee
--- /dev/null
+++ b/plat/msdos386/libsys/sys_isreadyr.s
@@ -0,0 +1,28 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! 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 bx, sp
+	mov ax, 0x4406
+	mov bx, 2(bx)
+	int 0x21
+	jnc ok
+	movb al, 0
+ok:
+	cbw
+	ret
diff --git a/plat/msdos386/libsys/sys_rawcreat.s b/plat/msdos386/libsys/sys_rawcreat.s
new file mode 100644
index 000000000..67bc34e59
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawcreat.s
@@ -0,0 +1,24 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! 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:
+	movb ah, 0x3c
+	mov bx, sp
+	mov dx, 2(bx)
+	mov cx, 4(bx)
+	int 0x21
+	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..992c4c655
--- /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 bx, sp
+	mov dx, 4(bx)
+	mov cx, 6(bx)
+	movb al, 8(bx)
+	mov bx, 2(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..301e2fded
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawopen.s
@@ -0,0 +1,24 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! 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:
+	movb ah, 0x3d
+	mov bx, sp
+	mov dx, 2(bx)
+	movb al, 4(bx)
+	int 0x21
+	jmp .sys_axret
diff --git a/plat/msdos386/libsys/sys_rawrw.s b/plat/msdos386/libsys/sys_rawrw.s
new file mode 100644
index 000000000..a306d6528
--- /dev/null
+++ b/plat/msdos386/libsys/sys_rawrw.s
@@ -0,0 +1,33 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Read/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_rawread
+__sys_rawread:
+	movb ah, 0x3f
+	.data1 0x3d			! eat up the next instruction
+.define __sys_rawwrite
+__sys_rawwrite:
+	movb ah, 0x40
+	mov bx, sp
+	mov dx, 4(bx)
+	mov cx, 6(bx)
+	mov bx, 2(bx)
+	int 0x21
+	jmp .sys_axret
diff --git a/plat/msdos386/libsys/sys_xret.s b/plat/msdos386/libsys/sys_xret.s
new file mode 100644
index 000000000..57f407ef4
--- /dev/null
+++ b/plat/msdos386/libsys/sys_xret.s
@@ -0,0 +1,41 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! 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 a shortword -1.  If the carry flag is clear, just
+! return a shortword 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 a longword -1 or dx:ax as a
+! return value.
+
+.extern .sys_zret
+.extern .sys_axret
+.extern .sys_dxaxret
+.sys_zret:
+	jc error
+	xor ax, ax
+no_error:
+	ret
+.sys_axret:
+.sys_dxaxret:
+	jnc no_error
+error:
+	push ax
+	call __sys_seterrno
+	pop cx
+	ret
diff --git a/plat/msdos386/libsys/unlink.s b/plat/msdos386/libsys/unlink.s
new file mode 100644
index 000000000..912f6958d
--- /dev/null
+++ b/plat/msdos386/libsys/unlink.s
@@ -0,0 +1,23 @@
+#
+! $Source$
+! $State$
+! $Revision$
+
+! Declare segments (the order is important).
+
+.sect .text
+.sect .rom
+.sect .data
+.sect .bss
+
+.sect .text
+
+! Remove a file.
+
+.define _unlink
+_unlink:
+	mov bx, sp
+	mov dx, 2(bx)
+	movb ah, 0x41
+	int 0x21
+	jmp .sys_zret
diff --git a/plat/msdos86/libsys/brk.c b/plat/msdos86/libsys/brk.c
new file mode 100644
index 000000000..ab333e550
--- /dev/null
+++ b/plat/msdos86/libsys/brk.c
@@ -0,0 +1,59 @@
+/* $Source$
+ * $State$
+ * $Revision$
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include "libsys.h"
+
+#define STACK_BUFFER 128 /* number of bytes to leave for stack */
+
+extern char _end[1];
+static char* current = _end;
+
+int brk(void* newend)
+{
+	/* This variable is used to figure out the current stack pointer,
+	 * by taking its address. */
+	char dummy;
+	char* p = newend;
+	
+	if ((p > (&dummy - STACK_BUFFER)) ||
+	    (p < _end))	
+	{
+		errno = ENOMEM;
+		return -1;
+	}
+		
+	current = p;
+	return 0;
+}
+
+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;
+		
+	return old;
+
+out_of_memory:
+	errno = ENOMEM;
+	return OUT_OF_MEMORY;
+}
diff --git a/plat/msdos86/libsys/build.lua b/plat/msdos86/libsys/build.lua
index 58bf3e6e5..96988002d 100644
--- a/plat/msdos86/libsys/build.lua
+++ b/plat/msdos86/libsys/build.lua
@@ -1,6 +1,7 @@
 acklibrary {
     name = "lib",
     srcs = {
+		"./brk.c",
 		"./close.s",
 		"./errno.s",
 		"./getpid.s",