Unknown 8085 opcodes

[Tony Duell]

On Wed, Jan 11, 2017 at 5:10 PM, Adrian Graham
<binarydinosaurs at gmail.com> wrote:
> Hi folks,
>
> Any 8085 assembler geeks in the house?
>
> Official Intel docs don't seem to be helping with this one, I have 8085 and
> D8741A peripheral controller dumps both containing several opcodes that two
> disassemblers aren't recognising and any docs I've been looking through for
> either 8085 instructions or the UPI instruction set don't seem to feature
> them either.
>
> The codes are 0x08, 0x10, 0x18, 0x28, 0x38,0xD9, 0xDD and 0xED.
>
> 0x08 nearly always follows a 0x01 LXI B instruction, the others don't seem
> to have an obvious pattern.
>
> I've pondered if 0x10 is INC @R0 because the binary for that is 0001 000x
> where x is either 0 or 1.
> By the same reasoning 0xD9 could be XRL A,R1 (opcode 11011xxx) and 0xDD
> could be XRL A,R5 but can't match the others. Also the surrounding code
> doesn't mention those registers.
>
> Example 8085 code fragment:
>
> 3440   1792 09                  DAD B
> 3441   1793 01 01 08            LXI B,0801H
> 3442   1796 08                  UNRECOGNIZED
> 3443   1797 12                  STAX D
> 3444   1798 0D                  DCR C
> 3445   1799 54                  MOV D,H
> 3446   179A 65                  MOV H,L
> 3447   179B 6C                  MOV L,H
> 3448   179C 65                  MOV H,L
> 3449   179D 70                  MOV M,B
> 3450   179E 68                  MOV L,B
> 3451   179F 6F                  MOV L,A
> 3452   17A0 6E                  MOV L,M
> 3453   17A1 65                  MOV H,L
> 3454   17A2 20                  RIM
> 3455   17A3 44                  MOV B,H
> 3456   17A4 65                  MOV H,L
> 3457   17A5 74                  MOV M,H
> 3458   17A6 61                  MOV H,C
> 3459   17A7 69                  MOV L,C
> 3460   17A8 6C                  MOV L,H
> 3461   17A9 73                  MOV M,E
> 3462   17AA 01 04 05            LXI B,0504H
> 3463   17AD 08                  UNRECOGNIZED
> 3464   17AE 17                  RAL
> 3465   17AF 53                  MOV D,E
> 3466   17B0 65                  MOV H,L
> 3467   17B1 6C                  MOV L,H
> 3468   17B2 65                  MOV H,L
> 3469   17B3 63                  MOV H,E
> 3470   17B4 74                  MOV M,H
> 3471   17B5 20                  RIM

I'm no programmer, but that looks like ascii text to me. Have you
tried decoding it
as such?

-tony