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

Name	Small Computer Monitor
Configuration	S5
Release	2022-10-16
Download ROM image	SCM S5 2022-10-16 (HEX)
Download source code	SCW 2022-10-16
Device Programming:
Code size	32k bytes
Checksum (MiniPro 6.6)	07D2 E8FF (SST39SF040)
Recommended IC	SST39SF040
Core Components:
Monitor	Version 1.3.1
BIOS	RC/Z180 1.3.1 (native)
Included Apps:
– ROM BASIC	Version 4.7b.1
– CP/M loader from CF card	Version 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.

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

• Z180 CPU (eg. Z8S180xx) at 18.432 MHz
• Z180’s asynchronous serial ports
• Z180’s timer (for idle events)
• SIO #1 at 0x80 (eg. Z84C4xxx) [rc addressing]
• SIO #1 at 0x80 (eg. Z84C4xxx) [zilog addressing]
• SIO #2 at 0x84 (eg. Z84C4xxx) [rc addressing]
• SIO #2 at 0x84 (eg. Z84C4xxx) [zilog addressing]
• CTC #1 at 0x88 (eg. Z84C30xx)
• CTC #2 at 0x8C (eg. Z84C30xx)
• ACIA #1 at 0x80 (eg. 68B50)
• ACIA #2 at 0x40 (eg. 68B50)
• CF Card at 0x10 for loading CP/M
• Diagnostic LEDs and digital I/O at 0x00

The SIO can either use the RC2014 addressing scheme or the typical Zilog scheme (as used by Dr. S. Baker’s SIO module)

The addresses of the official RC2014 SIO and ACIA modules clash, so they can’t both be installed at the same time. Also, it needs a 7.3728 MHz clock source. Third-party modules often have address options and onboard clock sources to avoid these problems.

The official RC2014 SIO module does not have tight address decoding so it appears as an SIO at both 0x80 and 0x84. Also, it needs a 7.3728 MHz clock source.

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 and memory:
  • SC111, Z180 Processor module at 18.432 MHz

• Memory:
  • SC119, Z180 Memory module
  • Marten’s Z180 Linear Memory Module (not tested)

• Serial port:
  • SC111, Z180 Processor module (Z180’s ASCI)
  • Karl’s #61, serial and storage (ACIA & CF)
  • SC104, serial module (Z80 SIO/2)
  • SC132, serial module (Z80 SIO/0) with 7.3728 osc.
  • SC139, serial module (68B50 ACIA)
  • and others

• Timer:
  • SC111, Z180 Processor module

• Baud rate generation:
  • SC111, Z180 Processor module

• CP/M storage:
  • RC2014, compact flash module
  • Karl’s #10, compact flash module (not tested)
  • SC145, compact flash module

• Self-test status display:
  • RC2014, digital I/O module
  • SC129, digital I/O module (eight LEDs)
  • SC134, LED outputs for RC2014 (eight LEDs)

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.

Release History

Config	Date	Monitor	BIOS	Base I/O
S5	2019-04-30	S5.0.03	Beta	0x40
S5	2019-06-02	1.0.2	1.0.1	0x40
S5	2022-02-27	1.3.0	1.3.0	0xC0
S5	2022-10-16	1.3.1	1.3.1	0xC0

Older Releases

Release 2022-02-27

Name	Small Computer Monitor
Configuration	S5
Release	2022-02-27
Download ROM image	SCM S5 2022-02-27 (HEX)
Download source code	SCW 2022-02-27
Device Programming:
Code size	32k bytes
Checksum (MiniPro 6.6)	07D2 F77B (SST39SF040)
Recommended IC	SST39SF040
Core Components:
Monitor	Version 1.3.0
BIOS	RC/Z180 1.3.0 (native)
Included Apps:
– ROM BASIC	Version 4.7b.1
– CP/M loader from CF card	Version 1.0

Release 2019-06-02

Name	Small Computer Monitor
Configuration	S5
Release	2019-06-02
Download ROM image	SCM S5 2019-06-02 (HEX)
Download source code	SCW 2019-06-02
Device Programming:
Code size	32k bytes
Checksum (MiniPro 6.6)	07D6 357F (SST39SF040)
Recommended IC	SST39SF040
Core Components:
Monitor	Version 1.0.2
BIOS	RC/Z180 1.0.1 (native)
Included Apps:
– ROM BASIC	Version 4.7b.1
– CP/M loader from CF card	Version 1.0