The base computer, as selected with the default options on this page, includes all the parts shown in the first picture. It has a Z180 processor, 512k bytes of RAM, two 512k bytes of Flash ROMs, two 115200 baud serial ports, and a micro SD card interface. You will need to provide your own micro SD. You will also require a power source that provides between 4.75 and 5.25 volts D.C. at up to 1 amp.

The kit is supplied with RomWBW pre-programmed into one of the Flash ROMs and the Small Computer Monitor (SCM) programmed into the other. RomWBW includes CP/M and a range of useful software. It also supports a wide range of add on hardware. RomWBW has been provided free of charge by its author Wayne Warthen. Thank you, Wayne, for providing this and all the support.

The Small Computer Monitor is a capable machine code monitor. The ROM also includes a version of BASIC and a CP/M boot loader (for CP/M installed on a Compact Flash card).

The base computer is formed from the following backplane and modules:

• SC701 - Backplane (see options for alternative designs)
• SC722 - Z180 CPU module (required, no options available)
• SC721 - 1MB memory module (required, no options available)

Backplane and Power Options:

• SC701 - Backplane with 6+1 module sockets and a 5 volt input
• SC709 - Backplane with 12+1 module sockets and a 5 volt input
• SC702 - Backplane with 6+1 module sockets plus SC703 PSU module
• SC710 - Backplane with 12+1 module sockets plus SC703 PSU module

SC703 is a power supply (8 to 12 volt input) and reset module. If this option is selected the supplied backplane will be either SC702 (6+1 sockets, no power input) or SC710 (12+1 sockets, no power input). If not selected the backplane will be either SC701 (6+1 sockets with 5 volt power input) or SC709 (12+1 sockets with 5 volt power input).

The backplane, SC701, has 6 vertical module sockets, 1 horizontal socket, a 5 volt power input, and a voltage supervisor and reset device. This backplane requires a power supply giving between 4.75 and 5.25 volts at up to 1 amp.

Alternative backplanes are available with a different number of module sockets. Some of the backplanes do not include the power and reset functions but instead provide header pins allowing them to extend other backplanes. These backplanes, SC702 and SC710, require a dedicated power and reset module, such as SC703 or SC712.

SC722 is the Z180 CPU module. This includes two serial ports, a status LED, and a socket for a Micro SD card adapter. The status LED acts as basic diagnostic indicator at start up and also acts indicates disk activity.

SC721 is a 1MB memory card. It includes 512kB of RAM and two 512kB Flash ROMs. One of the ROMs contains RomWBW and the other contains the Small Computer Monitor (SCM). A toggle switch selects the required firmware.

Recommended accessories and modules:

• SC302 - Serial to USB adapter
• SC303 - Micro SD card adapter
• SC305 - Adapter cable, 6-way
• SC306 - USB cable A to mini-B
• SC719 - Digital I/O module
• SC715 - Compact Flash module
• SC727 - Real time clock module

A number of options are provided to customise the kit. These include optional accessories and modules, and alternative parts, such as backplanes and power supply modules.

Documentation

The documentation can be found at www.smallcomputercentral.com

Compatibility

This module conforms to the RCBus specification v1.0 for RCBus-2014 and RCBus-Z80.

The RCBus specification includes RCBus-2014 (both RC2014 standard 40-pin bus and RC2014 enhanced 60-pin bus) and also the full 80-pin RCBus. The 80-pin RCBus provides support for advanced Z80 features, such as the interrupt daisy-chain, as well as support for other processor families.

The Kit

This kit, with the default options, includes all the components needed to make the computer, as shown in the first picture. Other modules and backplanes shown in the pictures are not included. You will require tools, solder, and cleaning materials to assemble this kit.

You will need to provide your own Micro SD card. If you select the Compact Flash module you will also need a Compact Flash card. Micro SD cards and Compact Flash cards between 64MB and 2GB are generally recommended.

A power source to match the options selected is also required. The power source will need to be either 4.75 to 5.25 volts at up to 1 amp, or 8 to 15 volts at up to 1 amp.

Printed Circuit Board

The printed circuit boards are available on their own here.

Notes

• This product is supplied as a kit of parts that require assembly.
• It is your responsibility to pay any import duty or taxes charged by your home country.
• This product is designed for hobby use and is not suitable for industrial, commercial or safety-critical applications.
• RomWBW is copyright Wayne Warthen and has been provided free of charge with his permission.
• The Compact Flash interface circuit has been designed by Tadeusz Pycio and reproduced with his permission.

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