1 .\" $Id: 6805_as.6,v 1.3 1994/06/24 14:01:39 ceriel Exp $
2 .TH 6805_AS 6 "$Revision: 1.3 $"
5 6805_as \- assembler for Motorola 6805
7 ~em/lib.bin/6805/as [options] argument ...
9 This assembler is made with the general framework
10 described in \fIuni_ass\fP(6). It is an assembler generating relocatable
11 object code in \fIack.out\fP(5) format.
14 The 6805 has an accumulator register A and an index register X. An
15 instruction (from the read-modify-write group) that references the
16 A-register has an "a" suffixed to the mnemonic. In a similar way
17 the X-register, apart from indexing operations, is addressed with
18 an "x" suffix, i.e. "lsra" and "negx".
19 .IP "addressing modes"
20 The assembler automatically selects the shortest opcode if
21 appropriate and possible. Thus "sub 10" will use the direct
22 addressing mode whereas "neg 0,x" will use indexed (no offset) mode.
23 There are sick constructions where the assembler can't find out
24 the shortest form in time. In those cases the longest form is used.
26 Branches are handled in much the same way. If a branch is out of
27 range it is replaced by a reversed condition branch, followed by
28 a jump, automatically.
31 .ta 8n 16n 24n 32n 40n 48n
34 #expr a one byte value (immediate)
35 <expr 1-byte zero page address. Allowed in
36 the register/memory and read-modify-
37 write instruction groups. (direct)
38 >expr 2-byte address. Allowed in the register
39 memory group. (extended)
40 expr 1-byte address if appropriate, 2-byte
41 in other cases. (auto-direct/extended)
42 ,x indexed with zero offset. (indexed)
43 <expr,x indexed with 8 bit offset. (indexed-1)
44 >expr,x indexed with 16 bit offset. (indexed-2)
45 expr,x indexed with the shortest possible off-
47 bit,expr bit number and direct address.
49 bit,expr,tag bit number, direct address and branch
50 tag. Automatically changed to reversed
51 condition branch and jump if appropri-
52 ate. (bit test and branch)
53 tag branch tag. Converted to reversed con-
54 dition branch and jump if appropriate.
57 .IP "PSEUDO INSTRUCTIONS"
59 .cmos assemble cmos version instructions.
65 M6805 HMOS, M146805 CMOS family, Motorola,
66 Prentice-Hall, Inc., 1983, (ISBN 0-13-541375-3).
69 Not a member of the ACK group.
71 The assembler has not been well tested.