Msg: 7082 *Conference*
04-09-97 18:05:41
From: RON WIESEN
To : COMET _
Subj: REPLY TO MSG #7074 (UNDOCUMENTED 80C85 OPCODES)
Your MSG_7090 regarding undocumented 80C85 opcodes is below with my corrections and additions. The "**" tag I recognize from Pages 23 and 24 of the ROM2 v5.1 user manual from Polar Engineering, fourth printing September 1, 1985. However, the mnemonics look like something born of the 8080. Wonder what source these mnemonics came from Comet? I've listed the mnemonics with respect to ROM2. Also, the last item "RSTV" (CB hexidecimal) doesn't appear in the manual - more on this later. There are three opcodes where the hexidecimal value is incorrect due to confusing "B" with "8" and vica-versa. I put a "?" beside these and show the correct value in a following line. ___________________________________________________________________|_MNEMON IC_ \** unspecified 8085 op codes: > (hl)= (hl) - (bc) DSUB 08 1 HLMBC > shift (hl) right; msb unchanged; (cy) = lsb ARHL 10 1 SHLR > rotate (de) left through carry RDEL 1B? 1 CORRECTION 18 RDEL > (de)= (hl) + * LDHI * 2B? 2 CORRECTION 28 DEHL byte > (de)= (sp) + * LDSI * 38 2 DESP byte > (l)= ((de)); (h)= ((de)+1) LHLX ED 1 LHLI > ((de))= (l); ((de)+1)= (h) SHLX D9 1 SHLI > if x5==1: jmp * JX5 * FD 3 JTM label > if x5==0: jmp * JNX5 * DD 3 JTP label > if overflow (v): call 40H RSTV C8? 1 CORRECTION CB unknown ___________________________________________________________________|_______ ___ Attached is file OP8085.DO which lists the 8085 instructions in three tables: Mnemonic Meanings by Functional Group, Actions by Functional Group, and by Mnemonic (alpha sorted). The mnemonics with syntax for assembly are as defined for the ROM2 assembler. Print it and insert it after page 22 of the ROM2 user manual. As for RSTV, nowhere in any of my sources do I find it. As far as it equating to an RST 8 which would call address 40H, in the Model T this is non-sensical because address 40H in the standard ROM is the beginning of a vector table for functions SGN to MID$. Consequently, these 16-bit vectors are not intended to be "fetched" as executible code. If the 8085 has such an instruction, then it's not germane to the Model T. Again I wonder, what source did you get this from? *Enclosed File: OP8085.DO