Sinclair ZX80 / ZX81 / Z88 Forums

Look at the price!!

Why would you want 2 tape inputs and 2 outputs?

The ram on one of my zeddys was also fashionably jaunty, as was the style at the time.

Ian

This is all fascinating stuff, thanks! Thanks moggy for the Jeff Minter link, lots to read there. With the ZX81 and the ZX Spectrum, there are reports in the magazines of the day suggesting a shockingly high rate of returns. Both for mail orders and for retailers. While my ZX81 & Kayde Rampack were ...

IMG_20201118_124034~3.jpg This is my Kayde Rampack, bought from (I think) WH Smith's in 1982, when they didn't have any Sinclair ones in stock. The case was a bit cheap, held together with those double sided sticky foam pads, but I never had any problems with it during its working lifetime 1982-198...

Hi all, On twitter I follow a fun bot called @yorecomputer, which tweets out random pages from scanned computer mags of the past. A few days ago, this tweet appeared, from issue 4 of Sinclair User magazine. https://twitter.com/yorecomputer/status/1466902125204680708?t=zJ13Q5jD_2nCgMQIk0dSEQ&s=19 It'...

1024MAK wrote: ↑Sun Jan 03, 2021 8:38 pm Why Wait - see this topic

Mark

Thanks for this - I've just fitted it using a BC307 and a 10K resistor, and it's working nicely.

Frames count from CLKFREQ.p benchmark has dropped from 1879 to 1717 so it's definitely running faster.

Thanks

Ian

Thanks for the responses and suggestions. I've had some success at last, using the tapeutils program. I was running Peppermint Linux on this laptop, it's got 2GB RAM and dual core CPU so it's not the slowest of wheezy laptops, but it's not blistering either. I think it's about 15 years old. Anyway, ...

OK.. think I've found the fault. It is tape loading related.. but not levels. Just listened to the audio when playing the larger .p files via JAVA tapeutils program on the Linux laptop - and there's gaps in it. This wheezy laptop seems to be struggling to give continuous sound output for the larger ...

Here is a simple program to test a machine that has 16k bytes of RAM: 16k RAM test program using DIM Please note that when this is run, the screen will immediately go black/blank. It takes about one minute to run on a 50Hz ZX81. Mark Damn, I wanted that to fail to be consistent with my expectations...

Your results are correct for the normal 16k byte upgrade. Thanks for confirming that. I did once know a bit about the ZX81 memory layout, but that was a long time back! Maybe you should instead post up some photos showing the work on your board that you have done? I was almost too ashamed as it loo...