Debugging CP/M 8080 code on the Z80-MBC2

August 24, 2022

I develop programs for the Z80-MBC2 in Intel 8080 Assembly with the Suite8080 8080 assembler. Aside from the binary compatibility, the Z80-MBC2 is a Z80 system, so I wondered what Assembly mnemonics and register set the CP/M development tools work with.

It turns out my favorite CP/M debugger, the SID symbolic debugger, comes in two versions specialized on the CPU, SID and ZSID.

SID accepts as input and outputs 8080 mnemonics and registers, ZSID Z80 mnemonics and registers. For example, in this CP/M 3.0 SID session on the Z80-MBC2 I loaded my Twirl 8080 program and disassembled it with SID's l (list) command:

A>sid f:twirl.com
CP/M 3 SID - Version 3.0
NEXT MSZE  PC  END
0180 0180 0100 D4FF
#l
  0100  MVI  C,09
  0102  LXI  D,0139
  0105  CALL 0005
  0108  LXI  H,0142
  010B  MVI  B,08
  010D  PUSH H
  010E  PUSH B
  010F  MVI  C,09
  0111  LXI  D,013E
  0114  CALL 0005
  0117  POP  B7

The output contains 8080 mnemonics. An analogous ZSID session running the same disassembly command outputs Z80 mnemonics:

A>zsid f:twirl.com
SID VERS 1.4
NEXT  PC  END
0180 0100 CDFF
#l
  0100  LD   C,09
  0102  LD   DE,0139
  0105  CALL 0005
  0108  LD   HL,0142
  010B  LD   B,08
  010D  PUSH HL
  010E  PUSH BC
  010F  LD   C,09
  0111  LD   DE,013E
  0114  CALL 0005
  0117  POP  BC

SID thus lets me work in a 8080 environment on a Z80 system.

#z80mbc2 #Suite8080 #CPM #Assembly

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