SC708 is a Z80 Single Board Computer (SBC) module designed for the RCBus. It is CP/M, just add a backplane and a Compact Flash module.
- SC708 – Assembly guide
- SC708 – Compatibility
- SC708 – Firmware (SCM S2)
- SC708 – Parts list
- SC708 – Printed circuit board
- SC708 – User guide
- Designing your RCBus computer
- SC700 series information
- SC700 series support
Downloads
- SC708, v1.0, Kit contents sheet (PDF)
- SC708, v1.0, Schematic (PDF)
- SC708, v1.0, PCB design files (OSHWLab)
- SC708, v1.0, Gerber files (ZIP)
Errata
Nothing known
Suppliers
| Kits | Website | Ships from |
| Stephen C Cousins | Tindie | UK |
| PCBs | Website | Ships from |
| Stephen C Cousins | Tindie | UK |
| Assembled and Tested | Website | Ships from |
| Not available | ||
| Components | ||
| See parts list |
Parts List
| Reference | Qty | Component |
| PCB | 1 | SC708, v1.0, PCB |
| C1 to C6 | 6 | Capacitor, ceramic, 100 nF |
| LED1 | 1 | LED, green, 3mm |
| P1 | 1 | Header, male, 2 row x 40 pin, angled |
| P2 | 1 | Header, female, 1 row x 6 pin, angled |
| P3 | 1 | Header, male, 1 row x 6 pin, angled |
| R1 | 1 | Resistor, 1k, 0.25W |
| R2 to R7 | 6 | Resistor, 10k, 0.25W |
| SW1 | 1 | Switch, tactile button, angled |
| Screw (for spacer) | 1 | Machine screw, 6mm, M3 |
| Spacer | 1 | Spacer, 10mm, M3, nylon |
| U1 | 1 | Z80 CPU, Z84C0008PEG, or Z80 CPU, Z84C0010PEG |
| U2 | 1 | RAM 128k bytes AS6C1008 |
| U3 | 1 | FLASH 128k bytes SST39SF010A |
| U4 | 1 | 74HCT4075 |
| U5 | 1 | 74HCT259 |
| X1 | 1 | Oscillator 7.3728 MHz |
| IC socket 40-pin U1 | 1 | Socket, DIP, 40 pin |
| IC socket 32-pin U2 and U3 | 2 | Socket, DIP, 32-pin |
| IC socket 14-pin U4 | 1 | Socket, DIP, 14-pin |
| IC socket 16-pin U5 | 1 | Socket, DIP, 16-pin |
Printed Circuit Board
Compatibility
This module conforms to the RCBus specification v1.0 for RCBus-2014 and RCBus-Z80.
User Guide
SC708 is a Single Board Computer (SBC) meaning it can work without any other backplanes or modules. It is based on a Z80 CPU running at 7.3728 MHz, with 128k bytes of RAM, 128k bytes of FLASH ROM (only 32k bytes is usable), and a simple bit-bang serial port. As a single board computer it is powered from the serial port.
The kit includes the Small Computer Monitor pre-programmed into the FLASH ROM. This includes a capable debug/monitor, BASIC, and a CP/M loader.
As there is no power-on reset circuit on this module, it is necessary to press the reset button to begin executing the firmware.
The board is CP/M ready, meaning it has a suitable processor and memory to run CP/M. Just add a backplane and a Compact Flash module to run CP/M. Ideally, a serial port module should also be added.
Input/output port functions
| I/O Address | Read | Write |
| 0x08 (0x08 to 0x0B) | n/a | Status LED (LED 1) Low = ON, high = OFF |
| 0x20 (0x20 to 0x23) | n/a | Serial RTS |
| 0x28 (0x28 to 0x2B) | Serial TXD | Serial TXD |
| 0x30 (0x30 to 0x33) | n/a | RAM bank select RA16 |
| 0x38 (0x38 to 0x3B) | n/a | Memory paging (lower 32k) Low = ROM, high = RAM |
Jumper options
| Jumper | Function |
| none |
Clock oscillators X2 and X3 are optional. The default is to connect the output of clock oscillator X1 to the CPU and the RCBus CLK pin. This requires a jumper shunt in each of the two marked default positions (JP1.1 and JP1.4). If you wish to use a clock sourced from a different module then the X1 jumper should be removed.
Fit a jumper shunt to JP2 if the voltage supervisor is to be used. This jumper connects the voltage supervisor to the RESET signal. The system should only contain one enabled supervisor, thus the jumper has been provided to isolate or connect this device.
Assembly Guide
Below is the suggested order of assembly. A general guide to assembling circuit boards can be found here.
- Header socket P2
This should lay flat against the PCB - Resistors R1 to R7
These can be fitted either way around - Decoupling capacitors C1 to C6
These can be fitted either way around - Sockets for U1 to U5
Fit such that the notch in the socket matches the curve in the outline on the PCB silkscreen - Bus header P1
Make sure the pins are parallel to the PCB so that the board is vertical when it is fitted into a backplane socket - Header pins P3
Ensure the pins are parallel to socket P2 - Light emitting diode LED1
Fit such that the short lead and/or small flat on the plastic is at the end marked with a line on the PCB silkscreen - Reset switch SW1
- Oscillator X1
Ensure the orientation matches the PCB silkscreen, noting the sharp corner at pins 1 - Insert the integrated circuits into their sockets
Make sure the notch in the component is at the end indicated by the notch in the socket and the curve on the PCB silkscreen - Fit the nylon spacer in the mounting hole
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.
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