Wednesday, 4 May 2022

Happy 2nd Birthday to the Minstrel 4th

It was two years ago today that the Minstrel 4th was launched.

Yes, I did rush to get it ready so I could release it on May the 4th. I resisted titling the post "May the 4th be with you", and instead went for "Minstrel Goes Forth"

It's done quite well in that time, several pieces of hardware specifically designed for the Minstrel 4th have been released

Along with many games, including one which has had a commercial release.

I suppose you could also say it has had a book written about it.

I though it would be interesting to have a look in more detail at some of these things and try them out.

The Minstrel 4th

First off, there is the Minstrel 4th itself. This is a Z80 based computer kit, which is compatible with the Jupiter Ace. As such, it uses Forth as it's main language, instead of the usual BASIC found in most other 8 bit machines. The Minstrel 4th has a built in keyboard, the maximum 48K+3K RAM and a RC2014 compatible expansion bus (The Minstrel 4th is "designed for RC2014"). Composite video output is provided by a condensed version of the Jupiter Ace video system, with microcontroller doing all the counting whilst still retaining video RAM and a shift register to generate the actual pixels.

At the time of writing, the 2020's have not been going too well for the world, and for various reasons the full kits are no longer available. There are some partial kits, with just the PCBs and the programmed parts available, you just have to find all the other parts yourself.

These are the ZX81 board sized versions, with an optional detachable keyboard.

Available from


6850 Serial board + Clock

On the initial release of the Minstrel 4th, I also had a serial card for it. This is a simple 6850 card, with a 7.37MHz clock on board. That can be configured to feed this clock to the RC2014 bus (if you want to run the Z80 faster), or just the 6850. The frequency is chosen so it can be divided down easily for standard BAUD rates, as used on the RC2014 and Grant Searle's Z80 SBCs.

I have also made several other serial boards over they years, but that is the only one available at the moment.

The Jester Ace

The Jester Ace by Dr Ian Johnson is an SD card interface for loading and saving programs on the Minstrel 4th.

It is available in kit for from their Tindie store

To use it, you type a command which loads the drive via a lead plugged into the ear port. Once loaded, you can use calls to directly load from the SD card.

USB keyboard interface for Minstrel 4th

This is a USB keyboard interface for the Minstrel 4th by Shiela Dixon. 

It allows you to type into the Minstrel 4th using a USB keyboard, and also allows you to "type" via a serial interface from a PC. 

They have provided a game for you to type in, but you can cheat and just copy and paste it into the terminal program and it will type itself in for you.

Several minutes later, it is complete, and you can run the game, Grand Theft Cygnus, based on their VIC20 game. Interesting to note that this version is written in forth and is able to use real Pythagoras to calculate the distances, where as the 6502 assembler version on the VIC used an approximation.

You can download the listing for the game and find links to buy the USB interface from their website:

Hmm, it says you can use any USB keyboard......

Yes you can. This is a Mini PET deluxe keyboard with a Commodore PET USB keyboard adapter plugged into the USB keyboard interface for the Minstrel 4th. Here's all the links if you really want to try that yourself

RC2014 Backplane and Modules

The Minstrel 4th only has one RC2014 slot, so you have to chose between your USB keyboard interface or your Jester Ace or your 6850 serial card.

That is unless you pick yourself up an RC2014 backplace. You can then also add from a range of other RC2014 modules. Not all will be compatible with the Minstrel 4th (no ROM or RAM etc.), but most of the IO options should be, such as this 8 channel digital input / output module.

These are all available from


Tut-Tut and 3D Monster Maze by George Beckett

This is a port of David Stephenson's Tut-Tut for the Jupiter Ace / Minstrel 4th by George Beckett. This was the launch title for the Minstrel 4th and has since been released on tape by Cronosoft

The source and binaries for Tut-Tut can be found, along with a lot of other Forth / Minstrel 4th code can be found on George's github

Also to be found there is a port of 3D Monster Maze, but in pure Forth, and a version with some Z80 machine code for extra speed and extra dinosaurs.

* there are no extra dinosaurs, sorry.

Snakez++ and Pac-Man by GLDM

Two nice ports from GLDM games

Available from their store

Demons of Dex by Petri Häkkinen

This is Demons of Dex by petrih, a dungeon crawler type game that I don't pretend to understand. One of the only titles I am aware of that makes use of the 6.5MHz speed option on the Minstrel 4th for smoother gameplay.

Jurdle by Kian Ryan

This is a fairly recent release and is an unapologetic rip off of Wordle.

Not sure what I was doing wrong, but I tried a few times and never got any of the letters right?

Old School Demo by ESi

This is not specifically for the Minstrel 4th, but it is a recently released demo for the Jupiter Ace that is rather impressive. 

Just an example that anything that runs on a Jupiter Ace should also run on a Minstrel 4th.

Thank you to everyone that has produced hardware or software for the Minstrel 4th. Let me know if I've got anything wrong or missed anything out.

I shall allow the Old School Demo the final words

Other than to say this post is a combination of new bits and a summary of various posts from my Patreon. If you want to get early access to these posts and other behind the scenes updates, you can follow along and support via Patreon -

May the Forth be with you.