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- .\" $Header$
- .TH 6800_AS 1
- .ad
- .SH NAME
- 6800_as \- assembler for Motorola 6800
- .SH SYNOPSIS
- /usr/em/lib/6800_as [options] argument ...
- .SH DESCRIPTION
- This assembler is made with the general framework
- described in \fIuni_ass\fP(6).
- .SH SYNTAX
- .IP registers
- The 6800 has two accumulator registers, A and B. An instruction that refers
- to accumulator A, has an "a" as last character. In the same way a "b" means
- that the instruction uses B as accumulator.
- .IP "addressing modes"
- .nf
- .ta 8n 16n 24n 32n 40n 48n
- syntax meaning (name)
- #expr with cpx, ldx, lds a 2-byte value,
- otherwise a 1-byte value (immediate)
- <expr 1-byte address. Not allowed with:
- asl, asr, clr, com, dec, inc, lsl, lsr,
- neg, rol, ror, tst (base page direct)
- expr 2-byte address (extended direct)
- expr, x 1-byte expr + contents of x
- yields address (indexed)
- .fi
- .SH "SEE ALSO"
- uni_ass(6),
- ack(1),
- .br
- A. Osborne, 6800 programming for logic design,
- Adam Osborne and Associates Inc., 1977
- .SH EXAMPLE
- An example of Motorola 6800 assembly code.
- .sp 2
- .nf
- .ta 8n 16n 32n 40n 48n 56n 64n
- .data
- val: 0
- .text
- ldx <val
- com val, x
- bhs someplace ! branch on carry clear
- sta <val
- adda #18 ! add 18 to accumulator A
- .fi
- .SH BUGS
- You have to specify whether an address fits in one byte
- with the token \fI<\fP. It should be done automatically.
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