Minstrel 3 for ZX81 case - Z80 based ZX81 kit

Name: Minstrel 3 for ZX81 case - Z80 based ZX81 kit
SKU: 36129
Price: 175.00 USD
Availability: InStock

A ZX81 compatible computer kit using modern ICs and one of the last Z80s ever made.

Designed by Tynemouth Software in United Kingdom

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 1

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 2

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Minstrel 3 for ZX81 case - Z80 based ZX81 kit 8

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 9

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 10

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 11

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 12

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 13

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 14

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 15

Minstrel 3 for ZX81 case - Z80 based ZX81 kit 16

2024-10-18T15:32:58.312Z-Minstrel 3 for ZX81 case.jpg

2024-10-18T15:32:58.312Z-Minstrel 3 kit knolled.jpg

2024-10-18T15:32:58.312Z-Minstrel 3 kit bagged.jpg

2024-10-18T15:32:58.312Z-Minstrel 3 kit packed.jpg

2024-10-18T15:32:58.312Z-Minstrel 3 PCB.jpg

2024-10-18T15:32:58.312Z-Soldering complete.jpg

2024-10-18T15:32:58.312Z-Keyboard connectors.jpg

2024-10-18T15:32:58.312Z-In ZX81 case.jpg

2024-10-23T15:44:26.543Z-ZX81 membrane.jpg

2024-10-18T15:32:58.312Z-Rex lies in wait.jpg

2024-10-18T15:32:58.312Z-Tut-Tut Title.jpg

2024-10-18T15:32:58.312Z-Tut-Tut Level 2.jpg

2024-10-18T15:35:53.902Z-25th Z80 inside.JPG

$175.00

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Sockets for all ICs?

The standard kit includes sockets for the three large chips only.

ZX81 Membrane?

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A ZX81 compatible computer kit using modern ICs and one of the last Z80s ever made.

What is it? This is a self assembly Z80 based computer kit. It is compatible with the Sinclair ZX81 computer released in 1981. It has been designed using modern 74HC series logic to be fully compatib…

What is it?

This is a self assembly Z80 based computer kit. It is compatible with the Sinclair ZX81 computer released in 1981. It has been designed using modern 74HC series logic to be fully compatible with the ZX81.

The board is designed to be the same shape and size as the ZX81 board, allowing this to be fitted into the case of a broken ZX81. Note the TS1000 case is similar, but the video output is in a different location, so a TS1000 case would require modification.

This version could also be used stand alone with your own keyboard or an aftermarket ZX81 keyboard.

This is a tried and trusted design, I have been selling these for 5 years now. The kit comes with all new modern parts which should mean every kit built works first time.

The Z80 has now been discontinued, but I have secured stock from one of the last batches of Z80 CPUs. All kits will be supplied with Z80s from that batch, date code 2427. While stocks last as they say.

Why did you make it?

An original ZX81 is a very minimal design with all the logic combined into a single chip. This ULA chip is a common point of failure, as are the vintage ROM and RAM chips. This is an ideal drop in replacement for a dead ZX81 board, or an upgrade for a functional one. This is an opportunity to build and program one of the first home computers.

What makes it special?

The upgrades from the original design include a full 32K of RAM on board. A ROM chip with the option of eight ROM images, and is supplied with ZX81 Floating Point BASIC ROM.

Unlike the ZX80 and Minstrel 2, this includes NMI "slow" mode, so is flicker free and compatible ZX81 software, including many high resolution graphics tricks.

The video output has been switched from a UHF modulator designed to drive a TV set to a composite video output that should suit a variety of TVs and monitors. It does not include a colour burst signal, so may confuse some composite to HDMI adapters. Jumpers can be used to select 50Hz or 60Hz frame rate for PAL or NTSC regions, and normal or inverse video.

The video signal has been cleaned up to add the back porch to the video signal, which was missing in all but the last revision of the ZX81. It also adds pixel synchronisation to ensure even sized pixels and no glitches from adjacent inverted and non-inverted characters. These improvements make very good solid picture on a modern LCD, just like the original would have been on a 1980s black and white portable TV.

Power is by 9V DC 2.1mm jack. Current consumption is around 80mA. Jumpers select either centre negative (ZX Spectrum, Commodore 16, guitar pedals) or centre positive (everything else).

The kit includes a 7805 linear regulator. No heatsink is required for normal operation, but if you plan to add a lot of expansions, you could fit a heatsink, such as the one from the donor ZX81.

All through hole parts are used making this kit suitable for an intermediate level kit builder upwards.

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$175.00