SC130, v1.0, User Guide

SC130 is a Z180 based motherboard. It can be used on its own as a Single Board Computer or it can be expanded using the built in module sockets. The Expansion sockets allow use of many modules designed for RC2014 and can be further expanded with a modular backplane, such as SC113.

SC130 normally has Flash memory containing RomWBW in socket U1.

Documentation for RomWBW here.

A short guide to getting started with RomWBW on SC130 can be found here.

Quick Guide to Jumpers

As a quick guide to getting started: Fit a jumper shunt in the position shown below and supply 5 volts to J1 or J2.

And for those who are sensible enough to read User Guides…


The power required for this board is 5 V D.C. at 100 mA without SD cards or other accessories. With accessories and expansion boards fitted the current requirement could easily rise to 300 mA.

The motherboard can be powered in a number of ways. The illustration below shows three places where 5 volts can be connected.

The board can also be powered from the serial ports or even the SPI port.

The motherboard is typically connected to a computer or terminal with an FTDI style serial adapter. This can, optionally, also provide power for the motherboard. However, some USB sockets and some FTDI style adapters will not provide adequate power if many accessories and expansion cards are connected.

Each serial port, highlighted below in red, can supply power to the system. To connect power from a serial port, fit a jumper shunt in the appropriate location, indicated below in yellow. The left jumper is for port A and the right jumper is for port B.

WARNING: You should normally only connect one power source to the system, at any time.

As power can flow either way, these jumpers also enable serial devices to be powered from the motherboard. If such devices are used, fit a jumper shunt in the appropriate position, indicated above in yellow.

Write Protect Flash

Jumper JP1, shown below in yellow, enables the Flash chip to be write protected. It is unlikely the Flash chip will be corrupted in normal operation due to the software requirements to write to it. However, for peace of mind you can disable writing with jumper shunts.

Fit the shunt in the position shown below in green to disable writing (to write protect the Flash memory). Alternatively, fit the shunt in the position shown below in red to enable writing.

Serial Ports

The motherboard has two asynchronous serial ports, with software selectable baud rate. These are 5 volt FTDI style ports.

The pin-out, below, describes signals with respect to the motherboard, so an output is a signal from the motherboard to a computer or terminal.

1Ground (GND)
2Request To Send (RTS) output
3Vcc (5V)
4Recieve Data (RxD) input
5Transmit Data (TxD) output
6Clear To Send (CTS) input (not connected)

The ground terminal is marked with a small down arrow to help with cable orientation.

A typical FTDI style serial adapter is illustrated to the right.

This may be fitted directly to the motherboard or by a 6-way cable.

The default serial ports settings are as follows:

Baud rate115200 (RomWBW v3.x)
38400 (RomWBW v2.x)
Data bits8
Stop bits1
Flow controlHardware

The default serial port connection is P6, Serial Port A.

SPI Port

The motherboard has an SPI port, primarily for connection of an SD card adapter.

The signals are 5 volt levels, with the following pin-out.

1Chip select (active low)
3Master out, slave in
4Master in, slave out
5Vcc (5V)
6Ground (GND)

The ground terminal is marked with a small down arrow to help with cable orientation.

A typical micro SD card adapter is illustrated to the right.

This may be fitted directly to the motherboard or by a 6-way cable.

The default SD card position is connector P2, SPI SD Card.

Expansion Bus Sockets

The expansion connectors are 40-pin RC2014 Bus compatible.

Pin numberSignal Name
37USER1 (not used)
38USER2 (not used)
39USER3 (not used)
40USER4 not used)

Memory Map

The physical memory map is simply 512k byte of Flash ROM at the bottom of memory and 512k bytes of RAM at the top of memory.

The Z180’s memory management unit deals with mapping chunks of this memory into the logical 64k memory map supported by the Z80/Z180 instruction set.

0x80000 to 0xFFFFFRAM (512k bytes)
0x00000 to 0x7FFFF Flash ROM (512k bytes)

Input / Output Ports

The motherboard’s I/O port addresses are as follows.

0xC0 to 0xFFZ180’s internal I/O registers
0x0EStatus LED port (write only)
Bit 0 = LED control (active low)
0x0DReserved for LED output port
(via expansion module SC129)
0x0CSystem I/O port (write only)
Bit 2 = SPI select (active low)

All other I/O addresses are available for use by expansion modules.

The status LED is initially turned on but is otherwise free to use. The LED can be written to with output statements or instructions.

  • Turn the status LED off from BASIC:
    • OUT 14, 1
  • Turn the status LED on from BASIC:
    • OUT 14, 0

Note that the LED is turned on by writing a 0 (not a 1). This is because the LED output is active low. This is necessary to allow the LED to be turned on by a hardware reset to indicate power is present. The reset signal clears the output latch to zero, thus zero is the on state.

The optional LED output port has 8 LEDs which are used to display diagnostic information at reset, but are otherwise free for use. These can be written to with simple input and output statements or instructions.

  • From BASIC:
    • OUT 13, <byte-to-be-output>
  • From the Small Computer Monitor
    • O D <byte-to-to-output>
  • From assembler:
    • LD A, <byte-to-be-output>
    • OUT ($D), A

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