uplm80 - PL/M-80 Compiler

A modern PL/M-80 compiler targeting Zilog Z80 assembly language.

PL/M-80 was the primary systems programming language for CP/M and other 8080/Z80 operating systems. This compiler can rebuild original CP/M utilities from their PL/M source code.

Repository: https://github.com/avwohl/uplm80

• Full PL/M-80 language support
• Targets Z80 instruction
• Multi-file compilation with cross-module optimization
• Multiple optimization passes (peephole, post-assembly tail merging)
• Generates relocatable object files compatible with standard CP/M linkers
• Produces code competitive with the original Digital Research compiler

Compiled output is comparable to the original Digital Research PL/M-80 compiler:

Quick install from PyPI:

pip install uplm80 um80 upeepz80

Platform-specific guides:

• Raspberry Pi: See README_RASPBERRY_PI.md
• General/Development: See INSTALL.md

Or install from source:

git clone https://github.com/avwohl/uplm80.git
cd uplm80
pip install -e .

uplm80 input.plm -o output.mac

Or run as a module:

python -m uplm80.compiler input.plm -o output.mac

Options:

• -t 8080 or -t z80 - Target CPU (default: Z80)
• -m cpm or -m bare - Runtime mode (default: cpm)
  • cpm: For new PL/M programs, maximum stack under BDOS
  • bare: Original Digital Research compatible (jump to start-3)
• -o output.mac - Output file name
• -O 0|1|2|3 - Optimization level (default: 2)
• -D SYMBOL - Define conditional compilation symbol (can be repeated)

Compile multiple source files together for optimal cross-module optimization:

uplm80 main.plm helper.plm library.plm -o output.mac

When multiple files are provided:

• All files are parsed together before code generation
• A unified call graph is built across all modules
• Local variable storage (??AUTO) is optimally allocated based on which procedures can be active simultaneously across module boundaries
• A single combined output file is generated

This produces better code than compiling files separately, as the compiler can share local variable storage between procedures in different modules that never call each other.

Use your preferred Z80 assembler and linker. Example with um80/ul80:

um80 output.mac                              # Assemble to .rel
ul80 -o program.com output.rel runtime.rel   # Link to CP/M .com

PL/M-80 is a typed systems programming language with:

• Data types: BYTE (8-bit), ADDRESS (16-bit)
• Variables: Scalars, arrays, structures, BASED variables (pointers)
• Control flow: DO/END, DO WHILE, DO CASE, IF/THEN/ELSE
• Procedures: With parameters, local variables, recursion
• Built-in functions: HIGH, LOW, DOUBLE, SHL, SHR, ROL, ROR, etc.
• I/O: INPUT, OUTPUT for port access

Example:

hello: DO;
    DECLARE message DATA ('Hello, World!$');
    DECLARE i BYTE;

    print: PROCEDURE(addr) PUBLIC;
        DECLARE addr ADDRESS;
        /* CP/M BDOS print string */
        CALL mon1(9, addr);
    END print;

    CALL print(.message);
END hello;

See examples/hello_cpm.plm for a complete working example.

For more on CP/M BDOS usage, see docs/BDOS_REFERENCE.md.

Later versions of PL/M-80 added conditional compilation directives embedded in comments. This allows the same source to be compiled for different configurations (e.g., CP/M 2.2 vs CP/M 3, single-user vs MP/M).

/** $set (CPM3) **/
/** $cond **/

DECLARE
/** $if CPM3 **/
    VERSION LITERALLY '30H',
/** $else **/
    VERSION LITERALLY '22H',
/** $endif **/
    MAXFILES BYTE;

Symbols can also be defined from the command line:

uplm80 pip.plm -D CPM3 -D MPM -o pip.mac

The compiler generates calls to these runtime routines (provide in a separate .rel file):

For new PL/M programs. Provides maximum stack space by using the area under BDOS:

• Program starts with ORG 100H (CP/M TPA)
• Stack is set from BDOS address at location 0006H: LD HL,(6) / LD SP,HL
• Maximum available stack (all memory between program end and BDOS)
• Entry code calls main procedure with CALL MAIN
• Returns to CP/M with JP 0 (warm boot) when main returns
• Requires CP/M stubs: MON1, MON2, MON3, BOOT
• System variables: BDISK, MAXB, FCB, BUFF, IOBYTE

For original Digital Research PL/M-80 compatibility. Programs begin with a jump to start-3:

• Entry begins with JP ??START to jump over local stack buffer
• Uses locally-defined stack (64 bytes in program image)
• Entry code at ??START sets SP to ??STACK label, then calls MAIN
• Compatible with original Digital Research programs (ED.PLM, PIP.PLM, etc.)
• Program can define custom entry point via DATA declarations
• No automatic OS return (program controls its own exit behavior)

uplm80/
├── compiler.py    # Main compiler driver
├── lexer.py       # Tokenizer
├── parser.py      # PL/M-80 parser
├── ast_nodes.py   # AST definitions
├── codegen.py     # Code generator
├── peephole.py    # Peephole optimizer
└── symbols.py     # Symbol table

This project is licensed under the GNU General Public License v3.0 or later - see the LICENSE file for details.

Contributions are welcome! Please feel free to submit issues and pull requests.

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