.\" $Id$ .TH Z80_AS 6 "$Revision$" .ad .SH NAME z80_as \- assembler for Zilog z80 .SH SYNOPSIS ~em/lib.bin/z80/as [options] argument ... .SH DESCRIPTION This assembler is made with the general framework described in \fIuni_ass\fP(6). It is an assembler generating relocatable object code in \fIack.out\fP(5) format. .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 8n 16n 24n 32n 40n 48n syntax meaning expr dependent on the instruction, the value of \fIexpr\fP 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 \fIexpr\fP yield the address of the operand. (expr) the value of \fIexpr\fP is the address of the operand. reg the contents of \fIreg\fP - one of the above- mentioned registers - is the operand. (reg) the contents of \fIreg\fP - 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), ack.out(5), .br Z80 Users Manual, Joseph J. Carr, Reston Publishing Company, 1980