1984-07-12 15:18:13 +00:00
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.\" $Header$
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1984-07-12 14:55:49 +00:00
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.TH z80_AS 1
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.ad
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.SH NAME
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z80_as \- assembler for Zilog z80
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.SH SYNOPSIS
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/usr/em/lib/z80_as [options] argument ...
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.SH DESCRIPTION
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This assembler is made with the general framework
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described in \fIuni_ass\fP(6).
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.SH SYNTAX
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.IP registers
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The z80 has six general-purpose 8-bit registers: b, c, d, e, h, l;
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an 8-bit accumulator: a; an 8-bit flag register: f; an 8-bit interrupt
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vector: i; an 8-bit memory refresh register: r; two 16-bit index registers:
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ix, iy; a 16-bit stack pointer: sp; and a 16-bit program counter: pc.
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The general-purpose registers can be paired to form three registers pairs of
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16 bits each: bc, de, hl.
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An alternate set of registers is provided that duplicates the accumulator,
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the flag register, and the general-purpose registers. The "exx"-instruction
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exchanges the contents of the two sets of general-purpose registers; the
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contents of the accumulator and flag register can be exchanged with the contents
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of their alternates by the "ex af, af2"-instruction.
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.IP "addressing modes"
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.nf
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1986-01-20 20:39:09 +00:00
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.ta 8n 16n 24n 32n 40n 48n
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1984-07-12 14:55:49 +00:00
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syntax meaning
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expr dependent on the instruction, the
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1986-01-20 20:39:09 +00:00
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value of \fIexpr\fP can be immediate
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1984-07-12 14:55:49 +00:00
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data or the address of the operand.
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There is no special notation for
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immediate data.
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(ireg + expr)
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(ireg - expr) the contents of ireg (which must be
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one of the index-registers) + or -
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1986-01-20 20:39:09 +00:00
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the - one byte - value of \fIexpr\fP
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1984-07-12 14:55:49 +00:00
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yield the address of the operand.
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1986-01-20 20:39:09 +00:00
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(expr) the value of \fIexpr\fP is the address of
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1984-07-12 14:55:49 +00:00
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the operand.
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1986-01-20 20:39:09 +00:00
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reg the contents of \fIreg\fP - one of the above-
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1984-07-12 14:55:49 +00:00
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mentioned registers - is the operand.
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1986-01-20 20:39:09 +00:00
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(reg) the contents of \fIreg\fP - one of the 16-bit
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1984-07-12 14:55:49 +00:00
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registers except pc - is the address of
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the operand.
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nz, z, nc, c,
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po, pe, p, m the letters indicate a condition-code:
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nonzero, zero, carry, no carry,
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parity odd, parity even, sign positive,
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sign negative respectively. Used by conditional
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jump, call, and return instructions.
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.fi
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.IP instructions
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The jr-instruction will automatically be replaced by a jp-instruction if the
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target is too remote.
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.SH "SEE ALSO"
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uni_ass(6),
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ack(1),
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.br
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Z80 Users Manual, Joseph J. Carr, Reston Publishing Company, 1980
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