A complete Unix/Linux implementation of Microsoft's classic CP/M development tools from the 1980s:

• um80 - MACRO-80 compatible assembler for 8080/Z80
• ul80 - LINK-80 compatible linker
• ulib80 - LIB-80 compatible library manager
• ucref80 - Cross-reference utility
• ud80 - 8080/Z80 disassembler for CP/M .COM files
• ux80 - 8080 to Z80 assembly source translator

These tools can assemble, link, and manage 8080/Z80 assembly code to produce CP/M-compatible .COM executables on modern Linux systems.

pip install um80

git clone https://github.com/um80/um80_and_friends.git
cd um80_and_friends
pip install -e .

um80 program.mac                    # Creates program.rel
um80 -o output.rel program.mac      # Specify output name
um80 -l listing.prn program.mac     # Generate listing file
um80 -g program.mac                 # Export all symbols as PUBLIC (for debug)
um80 -t program.mac                 # Truncate symbols to 8 chars (M80 compat)
um80 -e ".z80" program.mac          # Execute code before source (set Z80 mode)
um80 --pre macros.mac program.mac   # Include file before source

ul80 program.rel                    # Creates program.com
ul80 -o output.com a.rel b.rel      # Link multiple files
ul80 -s program.rel                 # Generate symbol file (.sym)
ul80 -S symbols.sym program.rel     # Specify symbol file name
ul80 -p E000 program.rel            # Set origin address (hex)
ul80 --prl program.rel              # Output MP/M .PRL format

ud80 program.com                    # Creates program.mac
ud80 -z program.com                 # Z80 mode
ud80 -e 0200 program.com            # Add entry point at 0200h
ud80 -d 0500-05FF program.com       # Mark range as data

ulib80 -c mylib.lib a.rel b.rel     # Create library
ulib80 -l mylib.lib                 # List contents
ulib80 -p mylib.lib                 # Show public symbols
ulib80 -x mylib.lib module          # Extract module
ulib80 -a mylib.lib new.rel         # Add module
ulib80 -d mylib.lib module          # Delete module

ucref80 program.mac                 # Print to stdout
ucref80 -o xref.txt *.mac           # Output to file

ux80 program.mac                    # Creates program_z80.mac
ux80 -o output.mac program.mac      # Specify output name

Microsoft MACRO-80 compatible assembler supporting:

• 8080 and Z80 instruction sets
• Macros with parameters (MACRO/ENDM)
• Repeat blocks (REPT, IRP, IRPC)
• Conditional assembly (IF/ELSE/ENDIF, IFDEF, etc.)
• Segments (CSEG, DSEG, ASEG, COMMON)
• PUBLIC/EXTRN for module linking
• Include files
• All standard directives (ORG, EQU, SET, DB, DW, DS, etc.)

Code can be injected before the main source file using -e (inline code) and --pre (include file). Both options can be repeated and are processed in the order specified:

# Set Z80 mode from command line
um80 -e ".z80" program.mac

# Multiple statements using ! separator (DRI notation)
um80 -e ".z80!DEBUG equ 1!BUFSIZE equ 256" program.mac

# Include a file of macros before the main source
um80 --pre stdmacros.mac program.mac

# Combine both, processed left to right
um80 -e ".z80" --pre macros.mac -e "MYVAL equ 42" program.mac

This is useful for:

• Switching CPU mode (.z80 or .8080) without modifying source files
• Defining conditional assembly symbols (DEBUG equ 1)
• Including project-wide macro libraries

See man um80 for full documentation, or refer to the original Microsoft M80 Manual.

LINK-80 compatible linker that:

• Links multiple .REL relocatable object files
• Resolves external references
• Produces CP/M .COM executables
• Supports COMMON blocks
• Can output Intel HEX format
• Can output MP/M .PRL (Page Relocatable) format
• Provides __END__ symbol for dynamic memory allocation

The linker provides a predefined __END__ symbol that points to the first free byte after all linked segments (code + data + common blocks). This is useful for implementing heap allocation:

        EXTRN   __END__         ; Import linker symbol

START:  LXI     H,__END__       ; Load end of program
        SHLD    HEAP            ; Initialize heap pointer
        ...

        DSEG
HEAP:   DW      0               ; Heap pointer

See man ul80 for full documentation, or refer to the original Microsoft L80 Manual.

LIB-80 compatible library manager for:

• Creating .LIB library archives
• Listing library contents and public symbols
• Adding/removing/extracting modules

See man ulib80 for full documentation, or refer to the original Microsoft CREF/LIB Manual.

Generates cross-reference listings showing:

• Symbol definitions
• Symbol references by file and line
• PUBLIC and EXTRN declarations

See man ucref80 for full documentation.

8080/Z80 disassembler that:

• Disassembles CP/M .COM files to .MAC source
• Produces output compatible with um80
• Supports both 8080 and Z80 instruction sets
• Allows marking data ranges and entry points
• Generates re-assemblable source code

See man ud80 for full documentation (no Microsoft equivalent exists).

Source-to-source translator that converts Intel 8080 assembly to Zilog Z80 assembly:

• Translates all 8080 instructions to equivalent Z80 mnemonics
• Preserves all comments, labels, and formatting
• Produces byte-identical output when assembled
• Automatically adds .Z80 directive to output
• Handles all assembler directives (passes them through unchanged)

Translation examples:

See man ux80 for full documentation.

These tools aim for compatibility with the original Microsoft tools while running on modern Unix/Linux systems:

• Source files use Unix line endings (LF), but CR/LF is also accepted
• File names are case-insensitive for symbols (converted to uppercase)
• Default origin is 0100h (standard CP/M load address)
• Output files are binary-compatible with original CP/M tools

The original Microsoft REL format limits symbol names to 8 characters. um80/ul80 extend this to support symbols up to 255 characters, which is essential for:

• External references with offsets (e.g., MEMSEGTBL+2 stays intact instead of truncating to MEMSEGTB)
• Long descriptive symbol names in modern code
• Compatibility with source code written for other assemblers

Use -t or --truncate to disable this extension for strict M80 compatibility.

See docs/EXTENSIONS.md for technical details on the extended REL format.

um80 supports several Digital Research (DRI) assembly syntax extensions commonly found in CP/M and MP/M source code. These extensions are compatible with DRI's ASM, MAC, and RMAC assemblers.

Multiple instructions can be placed on a single line, separated by !:

        PUSH H! PUSH D! PUSH B      ; Save registers
        POP B! POP D! POP H         ; Restore registers
        MOV A,B! ORA A! RZ          ; Test and return if zero

Extract the low or high byte of a 16-bit value using function-call syntax:

        MVI L,LOW(BUFFER)           ; Load low byte of address
        MVI H,HIGH(BUFFER)          ; Load high byte of address
        MVI A,LOW(1234H)            ; A = 34H
        MVI B,HIGH(1234H)           ; B = 12H

Both LOW(expr) and HIGH(expr) syntax (with parentheses) and LOW expr / HIGH expr syntax (with space) are supported.

The $ character can be used as a visual separator within numeric literals for readability:

        MVI A,1111$0000B            ; Binary with separator
        LXI H,1$0000H               ; Hex: 10000H
        MVI B,1$000D                ; Decimal: 1000

The $ characters are ignored during parsing and do not affect the numeric value.

Symbols can be defined with EQU to represent registers, then used in place of register names:

; Define register aliases using register names
UR      EQU     B                   ; UR is an alias for register B
LR      EQU     C                   ; LR is an alias for register C
MR      EQU     E                   ; MR is an alias for register E
KR      EQU     H                   ; KR is an alias for register H (or HL for pairs)

; Use aliases in instructions
        MVI MR,0                    ; Same as MVI E,0
        MOV A,UR                    ; Same as MOV A,B
        INR LR                      ; Same as INR C
        LXI KR,0                    ; Same as LXI H,0 (H maps to HL for pairs)

For register pair instructions, single register aliases are automatically promoted:

• B or C → BC
• D or E → DE
• H or L → HL

DRI assemblers allowed PUSH A and POP A as synonyms for PUSH PSW and POP PSW:

        PUSH A                      ; Same as PUSH PSW (push A and flags)
        POP A                       ; Same as POP PSW (pop A and flags)

Register number assignments (when using numeric values):

Symbols can be defined as aliases to external symbols with an optional offset, then exported as PUBLIC:

; In library module - define entry points
        EXTRN   ADD10           ; External symbol from another module
        PUBLIC  ADD10_SKIP      ; Export the alias

; Define alias: ADD10_SKIP is ADD10+2 (skip first instruction)
ADD10_SKIP  EQU ADD10+2

This is useful for:

• Defining alternate entry points into routines (skipping initialization code)
• Creating symbolic offsets into data structures defined in other modules
• Porting code from assemblers that support this feature (like z88dk)

The alias is resolved at link time:

; In main module - use both symbols
        EXTRN   ADD10
        EXTRN   ADD10_SKIP

START:  CALL    ADD10           ; Call full routine
        CALL    ADD10_SKIP      ; Call at offset (skips first 2 bytes)

For more details on these extensions and compatibility notes, see docs/EXTENSIONS.md.

• Man pages: man um80, man ul80, man ulib80, man ucref80, man ud80, man ux80
• Original Microsoft manuals in docs/external/:
  • m80.pdf - MACRO-80 assembler
  • l80.pdf - LINK-80 linker
  • cref_lib.pdf - CREF and LIB-80
  • 8080asm.pdf - 8080 assembly reference

# Assemble source files
um80 -o main.rel main.mac
um80 -o util.rel util.mac

# Create a library
ulib80 -c mylib.lib helper.rel support.rel

# Link everything together
ul80 -o program.com main.rel util.rel mylib.lib

# Run in CP/M emulator
cpm program.com

After pip installation, install the man pages manually:

# Find where the package is installed
PKGDIR=$(python3 -c "import um80; print(um80.__path__[0])")

# Copy man pages to system location (requires sudo)
sudo cp "$PKGDIR/../docs/man/"*.1 /usr/local/share/man/man1/
sudo mandb

Or view them directly:

man docs/man/um80.1

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• ioscpm - Z80/CP/M emulator for iOS and macOS with RomWBW HBIOS compatibility
• learn-ada-z80 - Ada programming examples for the uada80 compiler targeting Z80/CP/M
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