Sinclair ZX80 / ZX81 / Z88 Forums

Hi Ien, did you try out "grey border" jumper. Even if Processor is in reset state this should give a grey output, so shift register and things around that can be tested. If reset goes to high(check if it does) there should be some data seen in D0-D7. Next you may pull ram and eprom out of the board ...

After some experiments I am able to tell, that there are at least three ways to fix the pixel shift I noticed with 74HCT chips: - Replacing IC9 with 74HC08 See page 3 and 4 within https://d3s5r33r268y59.cloudfront.net/datasheets/18642/2019-11-27-20-17-38/Minstrel_Build_Instructions_v3.5.2.pdf - Chan...

Hi Mark, thank you for the welcome and the first hints to get minstrel's nose on the right place. First I was thinking about run-time issues within the digital circuits. Then I noticed that there are at least 3 RC elements existing in the minstrel (beneath audio part). One of them is located at cloc...

Hello forum members, admins and guests, as I am older than the internet, I was able to acquire an ZX81 in the begin of 1982. I tinkered around a lot with that device within these days until an Atari STE got my attention. At the and there was Memotech HRG, 56k Ram and some software working with my ZX...

Back in 1982 I bought my first computer: An issue 1 ZX81. A month ago I noticed Tynemouth Minstrel 3 ZX81 clone. Details at: http://blog.tynemouthsoftware.co.uk/2019/11/minstrel-issue-3-zx81-compatible-computer-kit.html https://www.tindie.com/products/tynemouthsw/minstrel-issue-3-zx81-compatible-com...