A from-scratch implementation of CP/M 2.2 (Control Program for Microcomputers) written in pure Intel 8080 assembly language. Lolos is a fully bootable operating system that runs on the z80pack emulator.

Note: This project is still under active development and testing. While core functionality works and passes automated tests, some edge cases may not yet be fully handled.

• Complete CP/M 2.2 implementation - All standard BDOS functions (0-37, 40)
• Full file system support - Including multi-extent files (>16KB)
• Built-in commands - DIR, TYPE, ERA, REN, SAVE, USER
• Transient program execution - Load and run .COM files
• 8080 compatible - No Z80 extensions, maximum portability
• Tested with real software - MBASIC, BBC BASIC, Colossal Cave Adventure

Build Requirements:

• zmac assembler (included in tools/ for Linux and Windows)

Runtime Requirements:

• z80pack emulator (cpmsim)

Test Suite Requirements:

• Python 3.8+
• cpmtools (cpmcp, cpmls) - for disk image manipulation

# Clone the repository
git clone https://github.com/yourusername/lolos.git
cd lolos

# Run automated tests (builds automatically)
python3 tests/run_tests.py

# Copy disk image to emulator
cp drivea.dsk ~/z80pack/cpmsim/disks/

# Run the emulator
cd ~/z80pack/cpmsim
./cpmsim

# Assemble components
./tools/zmac -8 --od src/boot --oo cim,lst src/boot/boot.asm
./tools/zmac -8 --od src/bios --oo cim,lst src/bios/bios.asm
./tools/zmac -8 --od src/bdos --oo cim,lst src/bdos/bdos.asm
./tools/zmac -8 --od src/ccp --oo cim,lst src/ccp/ccp.asm

# Create disk image
python3 tools/mkdisk.py

FFFFh ┌─────────────────────────┐
      │        (unused)         │
FBACh ├─────────────────────────┤
      │         BIOS            │  ~428 bytes
FA00h ├─────────────────────────┤
      │         BDOS            │  ~2.4K
EC00h ├─────────────────────────┤
      │         CCP             │  ~2K
E400h ├─────────────────────────┤
      │                         │
      │         TPA             │  ~57K
      │    (User Programs)      │
      │                         │
0100h ├─────────────────────────┤
      │      Page Zero          │  256 bytes
0000h └─────────────────────────┘

Console I/O (0-11)

• System reset, console input/output, string I/O, status

Disk Operations (12-37, 40)

• File open/close/create/delete/rename
• Sequential and random read/write
• Directory search
• Drive selection and status
• DMA address management
• User number support

• Type: IBM 3740 (8" SSSD)
• Tracks: 77
• Sectors/Track: 26
• Bytes/Sector: 128
• Block Size: 1024 bytes
• Directory Entries: 64
• Reserved Tracks: 2

The test suite requires Python 3.8+ and cpmtools.

# Run all tests
python3 tests/run_tests.py

# Verbose output
python3 tests/run_tests.py -v

# Skip rebuild
python3 tests/run_tests.py --no-build

# Run specific test
python3 tests/run_tests.py --test fileio

Initial compatibility testing with third-party CP/M software:

Additional software compatibility testing is ongoing.

lolos/
├── src/
│   ├── boot/boot.asm     # Boot loader
│   ├── bios/bios.asm     # Hardware abstraction
│   ├── bdos/bdos.asm     # System calls
│   └── ccp/ccp.asm       # Command processor
├── tools/
│   ├── zmac              # Assembler (Linux)
│   ├── zmac.exe          # Assembler (Windows)
│   └── mkdisk.py         # Disk image creator
├── tests/
│   ├── run_tests.py      # Test harness
│   └── programs/         # Test programs
├── lode/                 # Project documentation
└── drivea.dsk           # Output disk image

Files larger than 16KB span multiple directory entries (extents). Each extent contains:

• Up to 128 records (16KB)
• Its own allocation map (16 block pointers)
• Sequential extent numbers (EX field)

Lolos correctly handles extent transitions during sequential I/O.

The project uses zmac with 8080-only mode:

./tools/zmac -8 --od output_dir --oo cim,lst source.asm

• -8: 8080-only mode (no Z80 instructions)
• --oo cim,lst: Output .cim (binary) and .lst (listing)

def test_example(tester: CpmTester):
    """Test description"""
    tester.create_text_file("TEST.TXT", "content")
    success, output = tester.run_cpmsim(["TYPE TEST.TXT"], timeout=5)
    if "content" in output:
        return True, "Test passed", output
    return False, "Expected content not found", output

CP/M (Control Program for Microcomputers) was created by Gary Kildall in 1974 and became the dominant operating system for 8-bit microcomputers in the late 1970s and early 1980s. It ran on Intel 8080, 8085, and Zilog Z80 processors.

Lolos is an educational recreation that demonstrates:

• Operating system fundamentals
• File system design
• Hardware abstraction layers
• 8080 assembly programming

This project is provided for educational purposes. CP/M is a trademark of its respective owners.

• Gary Kildall for creating CP/M
• The z80pack project for the excellent emulator
• The cpmtools project for disk utilities