SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus

Name: SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus
SKU: 30811
Price: 130.00 USD
Availability: InStock
Rating: 5.00 (3 reviews)

(3 Reviews)

A single board Z80 computer in a motherboard format including RomWBW CP/M and SCM

Designed by Stephen C Cousins in United Kingdom

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 1

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 2

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 3

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 4

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 5

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 6

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 7

SC720 Z80 RomWBW CP/M Motherboard Kit for RCBus 8

2023-06-23T12:57:49.282Z-SC720 - Assembled C - 3x2.jpg

2023-06-23T13:32:41.276Z-SC720 - Kit parts A - 3x2.jpg

2023-06-23T13:32:41.276Z-SC720 - Assembled B - 3x2.jpg

2023-06-23T13:32:41.276Z-SC720 - Extension - 3x2.jpg

2023-06-23T19:06:08.952Z-SC700 series - 2023-06-05.jpg

2023-06-23T15:12:33.975Z-Serial optional extras - labelled - 3x2 - 3618x2412.jpg

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2023-06-23T15:12:33.975Z-SC720_v1.0.0_Render_red_bottom.png

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A single board Z80 computer in a motherboard format including RomWBW CP/M and SCM

Documentation

The documentation can be found at www.smallcomputercentral.com

Compatibility

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

Most RCBus, RC2014 and compatible modules can be used to expand this motherboard, including:

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 includes all the components needed to make the motherboard, 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 also need a power source (8 to 15 volts). A Compact Flash card is highly desirable to make full use of the kit's capabilities.

All the integrated circuits in this kit are brand new parts from major distributors in the UK or USA.

Printed Circuit Board

The printed circuit board is available on its 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.
The product contains small parts and is not suitable for young children.
The Compact Flash interface circuit has been designed by Tadeusz Pycio and reproduced with his permission.
RomWBW is copyright Wayne Warthen and has been provided free of charge with his permission.

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Review Breakdown

Average Ratings

Product: (5.00)

Documentation: (5.00)

Shipping: (5.00)

Communication: (5.00)

David | Nov. 11, 2023

The one you need!

This system rounds out my collection of SCC computers and is the culmination of several years of collecting. I love this system's design, as it combines pretty much the best of the z80 and z180 computer designs for the rcbus. I have plenty of modules and extensions I can use with this board, and it will quickly become my primary 8-bit workstation.

I'll be buying more computer kits in the future as gifts for friends and family, but this is the last of the SCC computers I'll need. If you aren't sure which system to get, and you want something that covers all of the basics and then some, this system will keep you happy for years to come!

Update after a couple days working with it:

This thing really is a motherboard! That's the best descriptor for it. It feels like a complete computer and, whenever I get some kind of display driver and PS/2 driver hardware installed in it, it will be easily standalone. The three slots are typically sufficient for expansion, though I do have a larger expansion board that fits it nicely. It starts to get a little unwieldy, but it sure looks cool! It really looks its best when it's got two cards installed directly on the board.

The build was very fun, too, I forgot to mention. It was different from the modular builds, with everything being on one board. Take your time and work section-by-section. While the build itself was less work than a full modular system, it can be a little intimidating when you first open the box. In the end, this build flew by quickly and I had a blast doing it.

The low profile compared to the modular systems is a nice change, though it is a little harder to display effectively when not in use. Overall, having RomWBW on a true Z80 system has been quite enjoyable. I even got a C compiling running on it!

Mike | Nov. 8, 2023

The kit worked first time.

I have been looking for a CP/M computer for some time and then I discovered the RCBus project and all the kits available. This kit provides all the basics with the ability to expand it with other modules in the future. In fact, I have just ordered a real-time clock board!

The instructions are clear with a sheet identifying all the parts. Initially, my kit was missing the pre-built Compact Flash adapter. But a quick email to Stephen fixed that problem before I had even got started building the board.

It took me 2 night to build the kit. The first to fit all the components to the board other than the chips. The second night was spent testing that the power supply was working and then plugging in the chips and figuring out how to use the software.

TIP: Having an integrated circuit leg straightener tool helped a lot (lookup 'IC leg straightener tool' on Amazon or Ebay)!

I had ordered the optional USB serial boards and | recommend them since they support hardware handshaking and they directly plug into the board and worked first time. Then came booting up the board! The SCM ROM booted fine, but the RomWBW got stuck with only 2 of the long row of green LEDs lit. It turned out that although I thought I had plugged in U10 properly, pin 20 had folded up underneath and wasn't connected. After I had straightened the pin and plugged the chip back in, everything worked. I plugged in an old 1GByte Compact Flash board into the adapter and that is recognized by RomWBW and now shows up as a disk drive.

An excellent kit, highly recommended!

Mogens | July 19, 2023

Excellent Z80 computer

This kit is an excellent, classic Z80 computer! It runs lots of software, including standalone BASIC and FORTH, two machine code monitors, and the classic OS’es CP/M 2.2, Z-System, and CP/M 3 - aka CP/M Plus.

Shipping is fast, and the kit arrives neatly packaged in a very compact cardboard box/envelope. Steve’s kits are always very high quality, and this one is no exception. I have bought and built several of the SC kits before and never had any issues. I also think the price of this board makes it a very good deal.

The package includes a parts list in print, and on the website, you will find all the detailed documentation you need for building and using this kit. You must add the power supply and a Compact Flash (CF) card yourself, otherwise, everything is in the package. You can run the board without the CF, but then you have no external storage. I have successfully tested a cheap micro SD to CF card adapter on the board, so that could be an option for you too.

I would say that you need “moderate/intermediate” soldering skills to build this kit; it’s not at all difficult, but there are many solder joints to do. If you follow the detailed assembly guide carefully, step by step, you won’t get lost in the process. Also, the PCB has a very nice layout, labeled with much detail as to which part goes where which is very helpful.

I like the RCBus which is compatible with RC2014 but adds enhancements. So there are lots of expansion boards compatible with the SC720, both from Steve and other sources as well. I like the use of a voltage regulator, providing a stable power supply for the board. The small LEDs with housing are a nice detail, adding to the good looks of the board.

In terms of software, the SC720 is well supported by two user-selectable flash ROMs, one with an excellent Monitor and BASIC, and the other one with RomWBW, which is a powerful set of tools, including CP/M. This software has been around for quite some time, and is very mature, stable and high quality; everything (HW+SW) is open source, thank you - this is great work crafted by some very enthusiastic people, highly appreciated. I mostly run CP/M 3 from Compact Flash, which just happens to be my personal preference.

The SC720 hardware and software offer many features, all integrated into one motherboard. If you like computing like in the ‘70s and ‘80s this is a good buy.

Conclusion: Highly recommended, high-quality kit!