After my eventual success with the Mini PET I bought a Minstrel 3 which is a ZX81 clone again designed by tynemouth software and was being sold by The future was 8 bit this particular version comes with a ZXpand SD card based file system.
This kit comes with less sockets than the Mini PET but the CPU, ROM and RAM are socketed, most of the ICs are HC series CMOS.
Bare board,bag of discrete components and instructions
The instructions are clearly written and also have a location guide for the components which shows the IC / resistor numbers (there is also one showing the IC types)
Components location guide
Sadly there is no complete schematic given (probably to hinder cloners) and the instructions split the computer into sections talking about each circuit section (which is clear and understandable), again no component identification guide so you’ll need to know what a capacitor, diode etc looks like before building it.
Partway through with the discretes on board
The build progressed fairly quickly starting with the lowest components working my up in height before adding the ICs soldering in directly (no sockets for most of these unlike the mini-PET) and this time I was little more careful to get the right ones in the right places, again the ICs are supplied in anti static foam matching their position on the board.
This PCB comes with the keyboard attached but with some care you could cut it off if you needed to put the board into a real ZX81 but for my purposes I’m going to be using the keyboard supplied.
After a lot of soldering it felt like it was time to fire things up for the first time.
working Minstrel 3
The screen doesn’t have the moire effect in the real world.
A quick row column test of the keyboard then it was time to move on the ZXpand which adds a SD card and joystick to the board.
I didn’t get a instructions for the ZXpand which was a small issue particularly since Dave Curran who designed the board at the time of writing has removed the tynemouth software blog content (read the blog for more details) however most of the content is available via archive.org and I managed to find a copy of the instructions for the version 1.4 of the ZXpand board via the old tynemouth software tindie page which I have mirrored
One thing I should point out that this board is specifically for the Minstrel 3 and won’t work on a ZX80 or ZX81. The only obvious change between version 1.4 and 1.5 I can see is adding a serial port to the board which the original ZXpand now supports (I’ve not checked if the firmware with the minstrel version supplied supports this).
ZXpand board with components
You could probably complete the board without any reference to the manual, but it’s nice to have for how to use the board.
After a bit more soldering (there is also a jumper wire to attach between the boards) and using the supplied 0.1” connector I have made a permanent connection between the ZXpand and Minstrel 3.
Minstrel 3 with ZXpand and keyboard
The keyboard switches were fitted and the stand offs have been fitted to the boards. It was then time to give the system a workout once I’d transferred some tape images onto a SD card.
So now I have very capable ZX81 clone with a modern SD card for storage.
Comparing this to the mini PET kit is interesting, the documentation is a little bit better (ignoring the ZXpand issue) but there are only sockets provided for some of the ICs on the board. The keyboard isn’t as nice for obvious reasons but to be honest I have plan for that in future so I’m not quite as bothered. I now have a fully expanded ZX81 with modern storage and no ram pack wobble.
The video seems very stable on my little 9” LCD from amazon so I’m happy and in some ways the keyboard feels more like something Sinclair would have produced in the past so it gives a retro feel. It also has the advantage over the mini PET in using off the shelf components for the video circuitry. Like the mini PET not a hard board to build but again some small levels of experience would be good.
I’m going to give the Minstrel 3 four and half stars out of five ⭐⭐⭐⭐½
Now if you’ll excuse me I have a monster to avoid….
3D monster maze