🇬🇧 Minstrel 2 (Sinclair ZX80 Clone): Part 2 (Pixel Synch. Issue) [TCE #0609]
34Thanks to PCBWAY for again sponsoring my video! https://www.pcbway.com/
Let's see if we can implement Dave's (Tynemouth Software) fix for the ZX80's pixel synchronisation issue on our Minstrel 2 v2.6 board. This issue wouldn't have been noticeable on a CRT back in the 1980s.
This fix is implemented in the current v2.9 version of Dave's Minstrel 2 board, and he has an excellent writeup about the issue and how he fixed it on his blog - part 1 can be found here:
http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.html
I created a small daughterboard by comparing Dave's v2.6 and v2.9 video output stages (thanks for schematics Dave!). My implementation can be found on my Github here:
https://github.com/0ddjob/Sinclair
HUOM!
This is purely for the Minstrel 2 v2.6 board - I don't have an original ZX80 to compare or test with.
The design & board works as it is, but I want to make some cosmetic changes (like reordering the bodge wires).
00:00 ... Intro
04:40 ... Thanks to PCBWAY!
05:23 ... Board is built
07:05 ... Testing!
09:20 ... Final thoughts
10:07 ... Channel thanks & Outro
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From Part 1:
Let's build the Minstrel 2, a ZX80 compatible computer from Dave Curran at Tynemouth Software. It's part of a series of computers that Dave has designed and refined over the years, including the Minstrel 3 (ZX81), Minstrel 4th & 4D (Jupiter Ace) and MiniPET.
It includes both 4K Integer BASIC and 8K Floating Point BASIC.
I got the kit a few years ago - mine is v2.6, where as the latest available is v2.9 which has some improvements over this board, including the ZX80 pixel synchronisation problem (see below).
Loading software via the tape interface was a bit tricky. Files are available in various formats such as .O, .P, and .P81. Using tools like mame-castool and another converter didn't really work. It was only when I found some already-generated WAV files that I could get it to work - these can be found here:
http://qrp.gr/zx80/software.htm
There is a cut-down version of the ZXpand available which makes loading files a lot simpler.
As I'm using an LCD display an artefact of the ZX80's original design becomes easily visible on the screen - Dave has a post about this on his blog and has fixed it in the current Minstrel 2 version:
http://blog.tynemouthsoftware.co.uk/2022/09/minstrel-2-pixel-synchronisation-part-1.html
Dave's Tindie store:
https://www.tindie.com/stores/tynemouth/
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https://karlcasey.bandcamp.com/
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