Small Computer Monitor v1.3

The Small Computer Monitor is a classic machine code monitor for Z80 based systems.

Version 1.3 builds on the framework added in v1.2. This enables most configurations to be created with simple text files thus reducing the need to manage so many code files. It also makes it easier to add support for new devices, such as serial interfaces. The increased code size required to support these new features means the fully-featured monitor does not fit in an 8k ROM.

Known Bugs and Limitations

  • Some configurations of SCM v1.3 fail to execute idle event routines (API 0x13 to 0x16)
  • Single stepping does not execute instructions that result in the program counter not changing, such as DJNZ when B > 1 and the relative jump is to itself


  • SCM v1.3 – Source and Tools – 2022-03-25 (ZIP)
    • Pre-built ROM images (HEX files) can be found in the folder: SCWorkshop/SCMonitor/Builds
    • Detailed documentation can be found in the folder: SCWorkshop/SCMonitor/Documentation
    • Source code can be found in the folder:
    • Apps designed to run from SCM are in the folder:

Supported Hardware

Other configurations can be found in the SCM v1.0, SCM v1.1, and SCM v1.2 distributions.

Older Versions

For the following hardware, see SCM v1.2

For the following hardware, see SCM v1.1

For the following hardware, see SCM v1.0

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