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man/6800_as.6

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+.\" $Header$
+.TH 6800_AS 6ACK
+.ad
+.SH NAME
+6800_as \- assembler for Motorola 6800
+.SH SYNOPSIS
+~em/lib/6800/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 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),
+ack.out(5)
+.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
+	.sect .text; .sect .data
+	val:	0
+	.sect .text
+		ldx	<val
+		com	val, x
+		bhs	someplace	! branch on carry clear
+		sta	<val
+		adda	#18		! add 18 to accumulator A
+.fi