A single board computer using Z180

Stephen Cousins has designed the 512Mbyte 18MHz SC126 in response to a challenge to make a high performance board compatible with the RC2014 schema. (The Z180 is rated up to 33MHz but I suppose there are system constraints on speed.)

RomWBW is the primary OS for SC126, offering CP/M, SD card, real time clock, and CF card support


This is a pretty cool machine.

It’s very close to a modern SB-180, something that, at the time, was positioned to take on the rise of the PC. To show that the 8-bit world could still put up a fight.

But the design is nice, it’s complete and useable out of the box, and it’s CHEAP. At least the kit is, but looks easy enough to put together.

I should know better than to buy one of these. What I SHOULD be doing is trying to resurrect by SB-180 (I have one in storage). But this is strangely compelling.

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I see the SC130 has appeared, looking like a slightly simpler build and perhaps a cheaper one:

It can run Fuzix, which has got the interest of Oscar Vermeulen (of PiDP-8 and PiDP-11 fame):


In a nutshell: 18MHz Z180 CPU with on-board MMU, 512K RAM, 512K ROM, an SD card for storage and serial ports for your terminal … Absolute top-of-the-line CP/M specifications that you would have paid a fortune for back in the day, but now shrunk down to $49 and the size of four credit cards.
But here’s where it starts to get sexy: multi-user, multi-tasking with Fuzix. Also, built in to the ROM are CP/M, the Z-System, Basic and Forth. A very fast RAM disk and a ROM disk with all essentials come as standard.

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Fuzix on the SC130 is truly amazing. The machine is fast enough to have two terminals open at the same time, and the software playground in the distribution disk image is fantastic. I’d never have imagined a Z80 could do all this. Recommended!


Welcome to the forum, Oscar, and thank you for your excellent work for the community. I have a PiDP-11/70 in my basement by the PDP-11/34 right now. :slight_smile:


The SC131 is nearly here too, a pocket CP/M computer.


  • Z180 CPU running at 18.432MHz
  • 512k Flash
  • 512k RAM
  • 2 serial ports
  • MicroSD card slot
  • No further expansion if possible


Now available on Tindie.
A complete kit of parts is $73 (+P&P) (requires an external 5V PSU).

Cheap is the important thing given raspberry pi would be seen as their big competitor for mind share.

This looks interesting.

And there goes my interest.

There is something rather attractive to me about a cased single board machine: if it can run CP/M or anything more sophisticated than that, so much the better. (I’m thinking Fuzix… but I’m sure other OSes hit the mark too.)

In unrelated news, I subscribed some years ago to the Spectrum Next kickstarter, and now at last I have a nicely cased single board system with a usable keyboard. It’s small and light enough to pop into a rucksack too. I’m hoping to see interesting developments with this - it’s an FPGA system with 1M of SRAM and plenty of ports and connectors, which just happens to come configured as a super-Spectrum. But it’s very reprogrammable.

Im glad to see songle board 8 bit tinkerbox computers being made. It fills a hobby niche and hopefully a pricepoint thst needs filling.

The old computers wont last forever… Though i dare say they have done a good job of ptting rhat statement to the test.

So even if i feel no particular attachment to the z80 it was the processor of cpm, and something that is modern world compatible that can demonstrate the old software on actual hardware rather than an amulator is a grand thing.

They have essentially identical systems that are expandable. Just difficult to make something designed to be wrapped in a plastic case expandable. But the schematics and software for this one and the others are likely mostly identical.


You have my attention.

It isn’t even the idea that wouldn’t do hat i might want. It is more an on principle sort of mindset.

I’ve seen this review lately (by Nostalgia Nerd), https://www.youtube.com/watch?v=ckYN_TwbGiQ, and it seems to be a quite amazing system with considerable depth and much to be explored. This may be one of the best dedicated nostalgia system to date.

… But the only terminal I have uses DB-25’s.

Which is why there’s an entire industry of break out boxes, null cable swappers, dongles, gender changers, voltage maters, and other converter things so that you can plug your terminal in to something modern.

But the point is that it is a CP/M computer and
I expect a DB/25 or DB/9 serial port. If they were smart
you would sell a second z80 box serial terminal.
PS. I building a nice TTL computer so I have a old serial terminal.

But most people do not have DB/* serial cables today. Most people do not have a dedicated serial terminal. I can’t even think of the last time an off the shelf PC came with the “legacy” connectors. I think I’m pushing 20 years since I’ve had one in my house.

These are not retro computers. These are modern Z80s for modern users that happen to run legacy software. Pretty sure I couldn’t buy a 18MHz Z80 with 512K of RAM and solid state storage in 1985 for $20.

For hobbyists, they also happen to be easy to assemble.

As I said at the very top. This is, literally, a modern SB180. I’m just curious what it takes to drive a USB printer nowadays. Can I just shove printer stuff over the connection (likely HPGL on modern printers) and have it work?

(Let’s not get hung up, please, on differences of terminology or personal preferences as to what’s an attractive project or what label a project does or doesn’t deserve.)

For my own part, I one or two rather old laptops which do have DB-9 ports, and I have a couple of USB to serial connectors which come in pretty handy. I’ve also got a rummage box with various null modem cables, gender changers and DB-9 to DB-25 converters, but unfortunately no general purpose patch device.

I’ve a feeling it’ll be quite hard to drive a USB connected printer from a retro machine - but it might be worth a try. I think some of the network connected printers will still speak a simple sensible protocol over TCP, but that’s still a step removed.

Well, I’d be a bit careful about that. It comes across a little as if you’re saying, “even though we have a dozen expandable Z80 SBCs already, I feel that losing expansion in a thirteenth design, even in trade for other capabilities (such as, “drop it in a bag without worry”) is a bad idea.”

And if you need to add a peripheral, why not add it to your other Z80 SBC that is expandable? What, you mean you own only one? Odd!

Actually, I think that TTL serial interfaces are as common, or even more common, than RS-232 these days, anyway. While myself I do have an RS-232 USB serial cable, that’s becuse I need it for devices such as my Apple IIc. But the majority of actual serial interfaces I use are TTL, not RS-232.

It depends on the printer, of course. Many have their own custom protocols and drivers.

I would hope that some might support the standard USB Printer protocol, which is basically just straight IEEE 1284 over USB. In such a case the SBC wouldn’t need to know anything about it; just run your PIA (6821 or whatever) into a microcontroller doing a fairly simple conversion of parallel IEEE 1284 to USB IEEE 1284.

But I’ve no idea if this is actually the case; I’ve not had my own printer in many years.

Yea, honestly today, I’m don’t know how much of the case that is, even today. At least not for simply printing.

HPGL has kind of been the de facto printer control language for a long, long time, and there’s little reason for it to be “reinvented”. Back in the day, you just opened the port and dumped data to the printer, and printing happened. For the simplest of use cases. Even the most advanced LaserJets would take raw text and print out 12 pt courier at 66 lines per page.

Similarly with Postscript printers, you could just “cat file.ps > /dev/printer” and pages showed up.

No, obviously, it’s different with scanners, page setup, faxing, and all that other modern stuff.

But rote printing, I bet it still works.

But I don’t know enough about USB as to whether you can just “cat file.txt > /dev/usb” and magic will happen.

There doesn’t seem to be a wide host of drivers in the linux world for a zillion different printers.

So, curious how that all works.