SC108 – Z80 Processor (RC2014)

SC108 is a Z80 processor module designed for the RC2014 bus. It contains a Z80 CPU, ROM, and RAM, making it a useful slot saving module.

A later design is now available: SC708

PCB v1.0 WARNING: If you fit an oscillator that has an enable/disable function on pin 1, you should remove pin 1 as the circuit board incorrectly grounds this pin.

Documentation

Downloads

Suppliers

KitsWebsiteFromCurrency
Small Computers DirectSCDirectUKGBP
Stephen C CousinsTindieUKUSD
Small Computer CentralLectronzUKEuro/USD
PCBsWebsiteFromCurrency
Small Computers DirectSCDirectUKGBP
Stephen C CousinsTindieUKUSD
Small Computer CentralLectronzUKEuro/USD
Assembled and TestedWebsiteFromCurrency
Not available
Components
See parts list
Small Computers Direct does not collect VAT for EU countries
Tindie does not collect VAT for EU countries
Lectronz does collect EU VAT for orders up to 150 EUR

Examples

IMG_20180709_155707837

Description

This module houses everything you need to run a basic RC2014 system, except for a serial module and backplane.

The main features of this module are:

  • Z80 CPU
  • 128k bytes RAM (second 64k not easy to use!)
  • 32k bytes ROM
  • Oscillator 7.3728 MHz
  • Reset (using DS1233-5)
  • Software compatible with standard RC2014 modules
  • Runs Small Computer Monitor v1.0 configuration R3
  • Add serial module (SIO or 68B50) for Monitor and BASIC
  • Add Compact Flash module for CP/M
  • Indicator to show if ROM or RAM is paged in

Parts List

ReferenceQtyComponent
PCB1SC108, v1.0, PCB
C1 to C5 5Capacitor, ceramic, 100 nF
C61Capacitor, ceramic, 1 nF
LED11LED, green, 3 mm
P1 1Header, male, 2 x 40 pin, angled
R1 to R4 4Resistor, 10k, 0.25W
R51Resistor, 470R, 0.25W
U11Z80 CPU, Z84C0008PEG
U1 socket140-pin DIP socket
U21RAM 128k bytes, AS6C1008
U2 socket132-pin DIP socket
U31EPROM OTP, 32k bytes, 27C256
U3 socket128-pin DIP socket
U4174HCT4075
U4 socket114-pin DIP socket
U5174HCT138
U5 socket116-pin DIP socket
U6174HCT74
U6 socket114-pin DIP socket
U71DS1233-5+ EconoReset
X11Oscillator 7.3728 MHz
X1 socket18-pin PDIP socket (optional)
Component details and sourcing

Printed Circuit Board

PCB v1.0 WARNING: If you fit an oscillator that has an enable/disable function on pin 1, you should remove pin 1 as the circuit board incorrectly grounds this pin. Fixed in v1.1

This board is made to the RC2014 Standard dimensions.

SupplierWebsiteShips from
Stephen C CousinsTindieUK
pcb4diyeBayGermany
pcb4diypcb4diy.deGermany
SC108, v1.1, PCB design files (EasyEDA)
SC108, v1.1, Gerber files (ZIP)

System Options

Below are some suggestions options for systems based on SC108.

Option A : Two Module SCM System

This two module system runs the Small Computer Monitor, which includes BASIC. It has no storage, but is adequate to write small machine code and BASIC programs.

Recommended firmware: Small Computer Monitor S3

Option B: Two Module CP/M System

Using Karl’s combined serial and compact flash module, a capable two module system can be built to run CP/M.

Recommended firmware: Small Computer Monitor S3
Recommended software: Standard RC2014 CP/M for ACIA

Option C: Three Module CP/M System

This CP/M system is built from three modules and offers software control of the second serial port’s baud rate.

Recommended firmware: Small Computer Monitor S3
Recommended software: Standard RC2014 CP/M for SIO

Option D: Three Module CP/M System

This CP/M system uses SC108 to replace some of the modules in the RC2014 Pro kit.

Recommended firmware: Small Computer Monitor S3
Recommended software: Standard RC2014 CP/M for SIO

Notes

  • This design is made in accordance with the “designed for RC2014” labelling scheme.
  • RC2014 is a trademark of RFC2795 Ltd.
  • 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.

Homebrew 8-bit retro computing