Firmware, SCM S4

The latest release of this Firmware is detailed in the table below.

NameSmall Computer Monitor
ConfigurationS4
Release 2019-06-02
DownloadSCM S4 2019-04-30
Device Programming:
Code size32k bytes
Checksum (MiniPro 6.6)????
Recommended ICAT27C256R-45PU
Core Components:
MonitorVersion 1.0.0
BIOSZ50Bus 1.0.0
Included Apps:
– ROM BASICVersion 4.7b.1
– CP/M loader from CF cardVersion 1.0

The firmware 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.

The Small Computer Monitor’s Components and Apps are described here.

Source code can be found in the Small Computer Workshop download.

Supported Devices

  • Z180 CPU (eg. Z8S180xx)
  • ACIA #1 at 0x80 (eg. 68B50)
  • ACIA #2 at 0x40 (eg. 68B50)
  • SIO #1 at 0x80 (eg. Z84C42xx)
  • CTC #1 at 0x88 (eg. Z84C30xx)
  • Digital I/O at 0x00
  • Compact Flash at 0x10 for loading CP/M
  • Status LED at 0x00

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

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

The Z180’s internal I/O is set to the range 0xC0 to 0xFF.


Installation – RC2014 ROM and RAM modules

Below are the jumper settings for the RC2014 64k RAM module and the RC2014 pageable ROM modules, when the Small Computer Monitor configuration S4 is programmed into a 27C256 (32k by 8) EPROM.Image

This image has an empty alt attribute; its file name is scm-s4-27c256-ram-64k-rom-pageable.jpg

Homebrew 8-bit retro computing