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