Sunday 24 September 2023

Minstrel and Mini PET Kit Updates

The full range of Minstrel 2 and 3 and Mini PET A and B kits are now available for sale again.

I have spent much of the last few weeks packing kits again, for the first time in quite a while.

And whenever I pack kits I like to build one of each to make sure everything is correct.


I'll start with the big news, Minstrel 2 and Minstrel 3 kits are now available from

This is the website setup by the creator of the RC2014 system to sell RC2014 modules and kits, so I think the Minstrel kits will be a good compliment to those. They also have better international shipping options that I can offer, so I hope that will help my international customers.

These are the full kits of the Minstrel 2 and 3, which can be fitted in a ZX81 case, or used stand alone with your own keyboard or the optional detachable tact switch keyboard.

Sell My Retro

I have also updated the range on SellMyRetro to include a range of options for each version. Yes, there are lots of options, I try to cater for all the different combinations that have been requested. If I don't have the combination you require, let me know and I will see what I can do.

Minstrel 2

The Minstrel 2 is a ZX80 compatible Z80 based computer with 16K of RAM and jumper selectable 4K integer BASIC or 8K floating point BASIC. The later is compatible with the ZX81 with the exception of SLOW mode, which is not supported by the ZX80 hardware (which mean most ZX81 games will not run).

The Minstrel 2 and 3 main boards are ZX81 sized, so can be fitted in a ZX81 case as a drop in replacement.

The detachable tact switch keyboard is optionally available if you want to run it stand alone, and can also be shared between the Minstrel 2 and 3.

I have recently started making more use of the detachable element to swap between versions with keywords for the 4K and 8K BASIC on the Minstrel 2.

To that end, I am now offering that in built and kit form with dual keyboards that you can swap as easily as you change the jumper from the 4K ROM to 8K ROM.

Minstrel 2 on Sell My Retro:

Minstrel 3

The Minstrel 3 is a ZX81 compatible Z80 based computer with 32K of RAM and 8K floating point BASIC. It does support slow mode, and several high resolution mechanisms, so the majority of ZX81 games will run fine.

As with the Minstrel 2, this is available in a variety of forms, including ZX81 case and standalone with tact switch keyboard.

Minstrel 3 on Sell My Retro:

Mini PET A

The Mini PET is a Commodore PET compatible 6502 based computer with 32K of RAM and a choice of PET BASIC 1,2 or 4, or Mini PET BASIC 4.0.

This is the stand alone version that can be used with one of my keyboards or another aftermarket PET keyboard (normal / graphics layout recommended for better compatibility than the business keyboard).

Mini PET A on SellMyRetro

Mini PET B

The B variant is designed as a drop in replacement for a PET motherboard. No keyboard options are provided, as you are expected to use the PETs original keyboard.

In addition to the DC power and composite video output of the A, the Mini PET B can use the PET power supply (5 pin or 9 pin) and drive a PET 9" or 12" monitor.

Mini PET B at SellMyRetro:

Mini PET Extras

I have also listed for the first time a few extra boards I designed to go with the Mini PET.


This is an adapter which can be plugged into the rear datasette port on a Commodore PET or Mini PET to provide power to an SD2PET whilst still providing a connection for a datasette drive.

SD2PET power tap on SellMyRetro:

PET Datasette interface.

This is a PCB which provides an interface to a Commodore datasette edge connector. The internal connection is a 6 way 0.1" connector (7 pin with 1 pin missing for polarisation).

This can be used to add the second datasette port to a Mini PET kit A, or for various extending one of the Mini PET datasette ports or for any other datasette interfacing projects.

PET datasette interface PCB on SellMyRetro:

PET Power Interface

Finally, something which was used with the original versions of the Mini PET. I later designed the B kit which integrated this board into the main board. It may still be useful for other things. It can be used to tap 9V DC from a PET power supply to power a Mini PET or other project inside a PET case.

PET Power Interface on SellMyRetro:


You can support me via Patreon, and get access to advance previews of posts like this and behind the scenes updates. These are often in more detail than I can fit in here, and some of these posts contain bits from several Patreon posts. 

This also includes access to my Patreon only Discord server for even more regular updates. I have been spamming the Discord with these new listings as they have been added over the last few weeks, to make sure they had first chance to get some of these things.

Sunday 17 September 2023

Commodore PET Keyboard Repair / Refurbishment

One from the Patreon Exclusive posts archive - a Commodore PET 8032 keyboard repair.

This is the keyboard from the PET 8032 as it arrived.

Looks like that needs a bit of work.

And a shift lock key, as that seems to be missing.

First job, strip it down and clean it up.

One of these things is not the same.

You might notice a yellow key at the top. This appears to be the return key from an early VIC20.

It looks very brown in the photo, but in normal lighting, you barely notice it.

Oddly my test keyboard also has a replacement return key, although mine was from a BBC mirco keyboard. (

With everything cleaned, time to address the shift lock.

I didn't have a PET keyboard for spares (or an early VIC20 with the same style keyboard), so I went for the shift lock key from a normal VIC20 / C64 keyboard. I was hoping it would be a drop in replacement.....

The only problem was it was too small to fit in the hole, clearly the earlier switches were larger.

My solution was Sugru. If you haven't come across that before, it's basically blu-tak that sets hard like rubber. (you can also remove it later if someone finds an actual PET style shift lock key)

I padded out the smaller shift lock switch with black Sugru and left it to dry.

The top side wasn't as neat, but still functional.

You get about half an hour before it goes off, so I fitted the keys either side to align it to them.

It is a different height, shape and colour, but you don't notice that normally.

I left that for several hours to go off, and then fitted the rest of the keys.

Normally, the pins of the switch poke out of holes on the back of the PCB, but with the switch being smaller, I had soldered them to the switch before I fixed it in place.

They then solder to the pads near the connector, where they are wired directly across the position of the normal shift key in the matrix.

All looking good, and just like the return key, you don't really notice the brown of the shift lock in normal light.

And with that, the keyboard was complete and ready to reunite with the rest of the PET.

I find it useful to test with one of my USB keyboard controllers, this proves the keyboard work, and any keys not responding just need to be run in, rather than a fault with the 6520 or the 74LS145 that drives the keyboard.

Some of the keys take a bit of pressing to register. They normally come back with use, but I haven't found a good solution yet to make them more responsive. There are various concoctions you can paint on the contacts, but they don't seem to last long.


PET USB keyboard controller / keyboard tester

As mentioned above, I use the USB keyboard adapters for testing keyboards.

All of these have jumpers to select business / graphics / chiclet keyboards.


I have a "universal" board which has a 20 pin connector for most keyboards and a 25 way D for 80xx-SK keyboards.

20 pin only

There is also a version without the 25 way D, if you don't need support for the 80xx-SK keyboards.


You can support me via Patreon, and get access to advance previews of posts like this and behind the scenes updates. These are often in more detail than I can fit in here, and some of these posts contain bits from several Patreon posts. This also includes access to my Patreon only Discord server for even more regular updates.

Sunday 10 September 2023

USB Keyboard Posts Back Online

When I closed my Tindie store, I took all the USB keyboard posts offline. Even if I wanted to build more, I couldn't get the microcontrollers at the time, so I thought it was a time to finish those off.

Later on, I had a bit of a tidy up and went through the stock of complete and partially complete boards, I realised I had quite a few left, so I listed those on my SellMyRetro store

Those were all listed as "these are the last stocks of the xyz USB keyboard controller", because at the time, that was the plan were.

And slowly, they sold, but I did get requests for ones that had sold out, or ones that I didn't have any left of anyway, so I was not able to help.

Roll on 2023, the microcontrollers started to appear back in stock, intermittently, as they would often sell out pretty quickly due to either big users of them or scalpers hoping to make a quick buck.

So I was able to bring a few of them back.

Now I have been able to put most of them back into stock, so I guess it is time to reactivate all the old posts and update all the links.

Remember, please use these ethically. They were initially designed to use up cases from broken machines, or to test keyboards. 

And to be clear, these allow you to use or test the keyboards from various old computers as USB keyboards on a modern PC, and not the other way around (e.g. A USB keyboard plugged into a ZX Spectrum).

All listings should now offer shipping to the UK, USA and Europe, let me know if I have missed any of them. Be aware that I am not able to collect VAT on international orders, so they will be sent as normal parcels via Royal Mail, and you may have to pay import duties or handling changes on arrival. There may also be delays, but there is not much I can do about that, I don't send the volume of parcels to be to setup all the EU IOSS type stuff.


I suppose I should start with the one that started it all, the ZX81. I have been through quite a few revisions of these boards, and now have two versions available, one for a ZX81 case, and an alternative to use a ZX81 membrane in your own case. (the reason for the difference is the orientation of the controller to the membrane, in the ZX81 case, it is upside down)



Amstrad CPC 464/6128

These are only suitable for keyboards with the white and green ribbons, there are a few variations in earlier CPC464s, but I think most of them are this type. Be sure to check before ordering.

I have also added stickers to make it clear which way around they connect.



VIC20 / Commodore 64

These have been various versions of these. I don't have all of them listed, but will be adding the USB keyboard with dual joystick version when I build the next batch of boards, as well as those for the Commodore 16, plus/4 and Commodore 128 if there is any interest in any of those.

For the moment, I have two listings, one with vertical pins that can be mounted at the back of the case, and also has a mode switch to select VICE positional or desktop mode, and one with right angled pin header for mounting on the back of the keyboard (or in tight spaces). I no longer supply the LED with the mode switch version as not many people appeared to use them, and the cable length and LED shape depends on the case you have and the position of the board. The pin header is still there if you wish to fit your own tricolour LED.



Commodore PET

I originally had three versions of this, one with just the pin header, one with just a 25 way D for the 80xx-SK PETs, and one with both. I have not listed the 25 way D only version, just the pin header and universal versions.



BBC Micro

These come in two versions, one with a piezo sounder to make the double beep power on sound. The other has a small audio amplifier to drive the original BBC speaker to make that sound.



Acorn Electron

The Electron keyboard is available mapped for normal desktop use, but also for use with Risc OS Pico, where the keys are mapped so that the keyword expansion works (i.e. press Func+F and F O R is typed as it would be on an Electron.






Oric 1 / Atmos



Atari ST

Not sure how I ended up with so many posts on the ST, but here it is



Amiga 500

There are three versions of the Amiga 500 USB and dual joystick controller boards. One has the USB socket on the pack panel for an external USB cable. The other two have an internal connection for a Raspberry Pi etc. One of those also has audio jacks that can pass through the output from a 3.5mm audio output. Note the version in the older blog posts with the DC-DC converter is no longer available.

There was even a blog post where I fitted an A500 mini into an A500 case with one of these controllers.



Amiga 600/1200



ZX Spectrum +2

This one has also been through many variations. I now have custom boards for the black Spectrum +2 A/B and for the grey Spectrum +2.



ZX Spectrum / ZX Spectrum +

I have left these until last as things are a bit complicated. I designed custom membranes for both the ZX Spectrum and ZX Spectrum+, and matching controllers.

I have no more of those membranes, and they were ridiculously expensive, so I don't think I would be able to get any more made. As such, I don't have a solution for the ZX Spectrum at the moment.

What about x, y, z?

Yes, I did produce quite a lot of others, some one offs, some larger runs. I may build more of the ones not currently listed, but will see how things go. Let me know if you are interested in any particular item.


Sell My Retro

As if this post was not already full of adverts, I suppose I should mention my SellMyRetro store also has a range of Minstrel 2, 3, 4th and Mini PET boards, kits and built units:


You can support me via Patreon, and get access to advance previews of blog posts and behind the scenes updates. These are often in more detail than I can fit in here. This also includes access to my Patreon only Discord server for even more regular updates.