5 ms·

If you had a ram expansion pack fitted an overly enthusiastic key press could cause it to wobble - it was only held in place by a connector which fitted onto th

If you had a ram expansion pack fitted an overly enthusiastic key press could cause it to wobble - it was only held in place by a connector which fitted onto the zx81’s circuit board iirc, and that could cause a power cycle

nickt 6y ago
Can confirm, definitely RAM pack wobble. Still makes me shudder! Memotech solved this problem by having a lower-profile RAM pack that included a piece of Velcro so the connector stayed secure. https://www.nightfallcrew.com/27/09/2013/memotech-memopack-16k-for-sinclair-zx-81/ https://www.nightfallcrew.com/27/09/2013/memotech-memopack-1...
mgkimsal 6y ago
IIRC there were ribbon cables for sale you could use to attach the ram pack to the zx81, eliminating the wobble. I seem to remember seeing ads for those in the back of some magazines. I know it was all about cost, but had Sinclair just bundled a ribbon cable connector, the entire "wobblegate" would never have been a thing.
djaychela 6y ago
Yes, I remember my friend who had the ZX81 originally took great pains to make sure the table was stable and you shouldn't knock it - we didn't realise how serious it was until it died when we were typing code in and it died. I think his dad ended up taping it in place so that it was less likely.
darrenf 6y ago
Can concur with all the other responders to this post. You could buy official "wobble stoppers", but my dad made one from corrugated cardboard and a LOT of gaffer tape. I used to type programme listings† in, blind, while my family watched something on TV. When I thought I was done, I'd ask them to switch the aerial cable over so we could play whatever game I believed I'd transcribed. Having suffered from unknown RAM pack wobble during the process was gutting, but on the flipside it was amazing when I'd got it right, or almost right - and whatever mistakes I'd made forced me to learn how to debug software. A skill that pays the bills almost 40 years on :) † from ZX Computing, or some multi-platform books from the library
- jansan 6y ago
  Awesome story, especially that blind typing. In Germany later (for the C64) we had a computer magazine that listed programs in hex code. There was a special hex editor to input these programs and each line had a check sum, so we could easily see if there was a typo in our program. But at one time there was a typo in the printed hex code, oh dear...

nickt 6y ago

Can confirm, definitely RAM pack wobble. Still makes me shudder! Memotech solved this problem by having a lower-profile RAM pack that included a piece of Velcro so the connector stayed secure. https://www.nightfallcrew.com/27/09/2013/memotech-memopack-16k-for-sinclair-zx-81/ https://www.nightfallcrew.com/27/09/2013/memotech-memopack-1...

mgkimsal 6y ago

IIRC there were ribbon cables for sale you could use to attach the ram pack to the zx81, eliminating the wobble. I seem to remember seeing ads for those in the back of some magazines. I know it was all about cost, but had Sinclair just bundled a ribbon cable connector, the entire "wobblegate" would never have been a thing.

djaychela 6y ago

Yes, I remember my friend who had the ZX81 originally took great pains to make sure the table was stable and you shouldn't knock it - we didn't realise how serious it was until it died when we were typing code in and it died. I think his dad ended up taping it in place so that it was less likely.

darrenf 6y ago

Can concur with all the other responders to this post. You could buy official "wobble stoppers", but my dad made one from corrugated cardboard and a LOT of gaffer tape. I used to type programme listings† in, blind, while my family watched something on TV. When I thought I was done, I'd ask them to switch the aerial cable over so we could play whatever game I believed I'd transcribed. Having suffered from unknown RAM pack wobble during the process was gutting, but on the flipside it was amazing when I'd got it right, or almost right - and whatever mistakes I'd made forced me to learn how to debug software. A skill that pays the bills almost 40 years on :) † from ZX Computing, or some multi-platform books from the library

jansan 6y ago
Awesome story, especially that blind typing. In Germany later (for the C64) we had a computer magazine that listed programs in hex code. There was a special hex editor to input these programs and each line had a check sum, so we could easily see if there was a typo in our program. But at one time there was a typo in the printed hex code, oh dear...