This is an old post, preserved for reference.
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This is the Tynemouth Software Minstrel Issue 2. It is a ZX80 clone with a few concessions to 2017. This fixes a few issue with the issue 1 boards (the missing link and the keyboard connector pinout)
improve the composite video output. These is now also a reset switch on board, and the list of the extra ZX80 commands that is on the ZX80 case is duplicated on the silkscreen.
modern replacement. Current draw is less than 200mA, more if you plan to draw any power from the expansion slot.
Build #1 - ZX80 Clone 4K ROM, 16K RAM
The ZX80 was originally supplied with a 4K BASIC ROM, and a keyboard with blue buttons. This is the classic ZX80. You can build the Minstrel to be a clone of this.ZX80-KDLX ZX80 style keyboard attached to connectors mounted on the bottom of the board. They do a ZX81 version as well, if you wanted to do one of those.
Build #2 - ZX80 Clone 8K ROM, 16K RAMWhen the ZX81 was released, Sinclair also provided an upgrade for the ZX80. A new 8K BASIC ROM, and a new keyboard overlay with grey keys, that looked just like the ZX81. This allowed it to run much ZX81 software, but it didn't have slow mode, so many of the more graphical programs wouldn't work. You don't see many of those around, as I expect most people prefer to see ZX80's with the blue keys. If you want grey keys, get a ZX81.
ZX81 membrane from RWAP. It's easier to work with the new ones as they are very flexible, the originals get very brittle in their old age.
Build #3 - ZX80 Clone 4K or 8K ROM, 16K RAM
The final of the three of these I have built has both ROMs installed, jumper selectable, and uses an RC2014 keyboard.
- Create a ZX80 clone using the 4K ROM and original keyboard layout.
- Create a ZX80 clone using the 8K ROM which will fit into a ZX81 case
- Create a ZX81 clone with NMI mode which will fit into a ZX81 case
Assembling a Minstrel ZX80 cloneAssembly should be fairly straightforward, they are all through hole parts. I've changed the silk screen to show values rather than part numbers, so it is just a case of putting 1K resistors in all the spaces marked '1K'.
2022 Update: PCBs, kits and occasional built kits are available from my SellMyRetro store.