SC192 – RCBus Z80 Computer | Small Computer Central

SC192 is a low profile modular Z80 computer designed to run the Small Computer Monitor (SCM) and BASIC.

Downloads

See individual product pages for downloads, such as kit contents sheets, schematics, PCB design files and PCB Gerber files.

Errata

Nothing known

Suppliers

*Kits*	*Website*	*Ships from*
See parts list
*PCBs*	*Website*	*Ships from*
Stephen C Cousins	Tindie	UK
*Assembled and Tested*	*Website*	*Ships from*
Not available
*Components*
See parts list

Parts List

SC192 is made up of the following modules:

Recommended accessories:

SC302 – Serial to USB adapter
SC305 – Adapter cable, 6- way
SC306 – USB cable, A to mini-B
SC134 – LED output module
Power supply, 8 to 15 volts at 500mA

The LED output module is recommended as it provides LEDs that display diagnostic information at startup. It is also useful for general I/O and and an easy way to add debug status during software development.

Compatibility

This system conforms to the RCBus specification v1.0 for RCBus-2014, 40-pin.

User Guide

SC192 includes the CPU, 128k RAM, 32k ROM, a 115200 baud serial port, and RCBus 40-pin expansion sockets. The ROM includes the Small Computer Monitor (SCM), BASIC and a CP/M loader. SCM is a capable machine code monitor.

To run CP/M you need a Compact Flash module and a CF card. the CF card must be prepared by formatting and installing CP/M. Install CP/M-C.

See individual product pages for more detailed information.

Assembly Guide

Build the modules as described on each product page.

See SCM_Apps for some useful test programs.

Recommended assembly and test steps:

Build the backplane and modules
Insert the power supply module (SC142) in any slot of the backplane.
Connect a power supply to SC142 (8 to 15 volts, up to 500mA)
Turn ON with the toggle switch on SC142.
The green ‘power’ LED should be on constantly.
The red ‘reset’ LED should light for about half a second and then go off. This indicates the voltage supervisor and reset device on SC142 is working correctly.
The red ‘reset’ LED should come on when the reset button is pressed and turn off about half a second after the reset button is released.
If possible measure the voltage out of SC142. It should be between 4.75 and 5.25 volts.
Turn OFF.
Insert the CPU module (SC149) and the ROM module (SC151) into any slots of the backplane.
Turn ON.
The LEDs on SC142 should act as before.
The LED on the ROM module (SC151) should act the same as the reset LED on SC142.
Turn off.
If you have the optional LED module (SC134) insert it into the backplane.
Turn ON.
The LEDs (if you have the optional LED module) should cycle continuously. This indicates the firmware is running and a RAM module has not been detected.
Turn OFF.
Insert the serial module (SC139) and ensure it is set to address 0x80.
Insert the RAM module (SC150).
Connect the serial module to a terminal or modern computer running terminal emulation software. Configure the software for 115200 baud, 8 data bits, 1 stop bit, no parity.
Turn ON.
The LEDs (if you have the optional LED module) should cycle once. This indicates the firmware is running and the RAM has been detected.
The LEDs on the ROM and RAM modules should be on but flash off following turn on or a press of the reset button. This indicates the firmware is running and the RAM has been detected.
One of the LEDs on the standard USB to serial adapter should be ON continuously. One of the pair of LEDs in the middle of the adapter should flicker briefly following reset. This indicates the serial module has sent the startup message to the terminal.
The terminal should shown the Small Computer Monitor start up message and the terminal should show responses to key presses.

Notes

This product is designed for hobby use and is not suitable for industrial, commercial, or safety-critical applications.
The product contains small parts and is not suitable for young children.