uplm80 0.2.12

Highly optimizing PL/M-80 compiler targeting 8080/Z80

uplm80 - PL/M-80 Compiler

A modern PL/M-80 compiler targeting Intel 8080 and 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

Features

• Full PL/M-80 language support
• Targets both 8080 and Z80 instruction sets
• 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

Code Quality

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

Program	DR PL/M-80	uplm80	Difference
PIP.COM	7424 bytes	7127 bytes	-4.0%

Installation

Quick install from PyPI:

pip install uplm80 um80 upeep80

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 .

Usage

Compile PL/M-80 to Assembly

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)

Post-Assembly Optimization (Optional)

python -m uplm80.postopt output.mac -o output_opt.mac

Performs multi-pass tail merging and skip trick optimizations.

Assemble and Link

Use your preferred 8080/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

Language Reference

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.

Conditional Compilation

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).

Directives

Directive	Description
/** $set (NAME) **/	Define a symbol
/** $reset (NAME) **/	Undefine a symbol
/** $cond **/	Enable conditional compilation
/** $if NAME **/	Include following code if NAME is defined
/** $else **/	Else branch
/** $endif **/	End conditional block

Example

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

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

Command Line

Symbols can also be defined from the command line:

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

Runtime Library

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

Routine	Description
??MUL	16-bit unsigned multiply
??DIV	16-bit unsigned divide
??MOD	16-bit unsigned modulo
??SHL	16-bit shift left
??SHR	16-bit logical shift right
??SHRS	16-bit arithmetic shift right
??MOVE	Block memory move

Runtime Modes

CP/M Mode (default: -m cpm)

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

Bare Metal Mode (-m bare)

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)

Project Structure

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
├── postopt.py     # Post-assembly optimizer
└── symbols.py     # Symbol table

License

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

Contributing

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

Acknowledgments

• Intel for creating PL/M-80
• Digital Research for creating CP/M
• The CP/M source code preservation efforts that made the original PL/M sources available