The latest release of this Firmware is detailed in the table below.
| Name | Small Computer Monitor |
| Configuration | F1 |
| Release date | 2019-06-02 |
| Download ROM image | SCM F1 2019-06-02 |
| Download source code | SCW 2019-06-03 |
| Device Programming: | |
| Code size | 32k bytes |
| Checksum (MiniPro 6.6) | 005C F912 |
| Recommended IC | AT27C256R-45PU |
| Core Components: | |
| Monitor | Version 1.0.2 |
| BIOS | Z50Bus 1.0.1 |
| Included Apps: | |
| – ROM BASIC | Version 4.7b.1 |
| – CP/M loader from CF card | Version 1.0 |
The ROM image is supplied (above) as an Intel HEX format file, which is suitable for use by most PROM programmers. Intel HEX files are a text format, not a binary format. As a result they are larger than the stated code size in the table above.
Source code is supplied (above) complete with the Small Computer Workshop development environment for Windows.
The Small Computer Monitor’s Components and Apps are described here.
Diagnostic display
At reset, the 8 LEDs next to the power LED are used to display the results of the self-test diagnostics. Each LED should light for a fraction of a second and the test should end with all 8 LEDs being turned off. Failures are indicated as follows.
| Display | Issue |
| Light sequence repeats indefinitely | RAM test failed |
| LED bit 0 remains on | Serial port test failed |
| No light sequence | CPU not running, or output port failed |
Supported Devices
- Z80 CPU (eg. Z84C00xx)
- SIO #1 at 0x80 (eg. Z84C42xx)
- SIO #2 at 0x84 (eg. Z84C42xx)
- CTC #1 at 0x88 (eg. Z84C30xx)
- CTC #2 at 0x8C (eg. Z84C30xx)
- Digital I/O at 0x52
- Compact Flash at 0x10 for loading CP/M
- Bit-bang serial port at 0x28
- Status LED at 0x08
The lack of specific support does not exclude the use of other hardware. It just means the ROM does not do anything specific with it.
Supported Modules
- Processor:
- Serial port:
- Baud rate generation:
- CP/M storage:
- via adapter to RC2014 compatible modules:
- Self-test status display:
- Z50Bus, digital I/O module (at 0x52)
The lack of specific support does not exclude the use of other hardware. It just means the ROM does not do anything specific with it.
Release Notes
When used with the on-board bit-bang serial port, the Small Computer Monitor’s software timed idle events run very slowly. This is due to the time the processor spends handling the serial port. When a Z80 CTC is present, the timing of idle events is not dependent on software delays and therefore runs at the correct speed.
