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Forum Index : Microcontroller and PC projects : ZX81 reborn....
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9626 |
I know that members here have been playing with the ZX81 on a Pico module(I think it was), but this video was interesting: ZX81 reborn... Smoke makes things work. When the smoke gets out, it stops! |
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7997 |
That's excellent! I had a ZX81 too (still have it somewhere). I still reckon the ZX80 and ZX81 were some of the best designs around. That's not because of the performance, but because of the technology. Every scrap of logic including the CPU was used to its utmost, it wasn't a case of throwing something powerful at the problem. I still think the token key system and Sinclair BASIC were brilliant too, especially on the Spectrum. They'd got the keyboard a bit more optimized by then and the raised keys really helped a lot. I think I may have been one of the few people that actually liked the Spectrum keyboard. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9626 |
Totally agree with all of that, Mick. It was quite amazing what people were able to do with that massive 1k of RAM! I had a 16k RAM-pack, but it was notoriously unstable, due to the edge-connector. It used to crash if you looked at it wrong!  Smoke makes things work. When the smoke gets out, it stops! |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7997 |
Well, yeah, the expansion port left a little to be desired. Bringing the Z80 pins out directly to a tinned (not gold plated) card edge connector was never the most brilliant scheme on any machine. Especially the case if something then hangs off said connector. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1258 |
The “keyboard” on my ZX81 broke after a few months. Because the foil was heated too much by the cooling plate and broke. As the cheapest alternative, I then put together clock buttons, which hung together in blocks of 5 as a keyboard. (we had nothing at the time )'no comment |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7997 |
I have a couple of ZX81s in the shed. One is still in its box. Unlike the ZX80 they aren't really worth much now though. I wonder if a ZX81 case and keyboard would be nice with a PicoMite in it? :) £11.99 for a new membrane. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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atmega8 Guru Joined: 19/11/2013 Location: GermanyPosts: 725 |
Yes ist was unstable because of the solder / tin on the connectors. Have lost many of typed in assemble code. Scrapped the tin of with a knife, and the problems disappeared immediately. |
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stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2600 |
I had zx81, ula gave graphic display while running code. but a pico mmbasic zx81 emulator .. dunno... and why bother??? |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2600 |
serious, why bother when pico will piss all over zx81?? just added the sound filter to pico hdmi usb. cost beer money...I'm an alcoholic  this is experimental for using gpio but simpler than the zx81 b0ard I used double sided tape to stick the boards down as experimental and it's great. Edited 2025-08-11 04:00 by stanleyella |
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| toml_12953 Guru Joined: 13/02/2015 Location: United StatesPosts: 449 |
Those of us who added an expansion interface to a TRS-80 keyboard grew very adept at using the Pink Pearl eraser (or rubber for the UK). That one connection helped the machine get the nickname Trash-80. |
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| toml_12953 Guru Joined: 13/02/2015 Location: United StatesPosts: 449 |
After scraping the connector, some of us jammed Blu-Tack (a type of reuseable adhesive putty) between the 16K RAM pack and the TS-1000 case to stabilize it. |
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| stanleyella Guru Joined: 25/06/2022 Location: United KingdomPosts: 2600 |
I liked the "putty" to hold components when soldering. I can't see the point of zx81 when pico is easy to wire and does so much more. |
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| gadgetjack Senior Member  Joined: 15/07/2016 Location: United StatesPosts: 170 |
The RadioShack here in the states had surplus TI99A keyboards for about 5 bucks. There were plans for wiring them up to zx81 for full travel keyboards. Had to glue a cut up print out of the zx81 keyboard to all the keys. Messy but it did work and was a lot easier to out type the basic then. I made 3 or 4 of those for friends. Ahh memories... |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7997 |
What makes you think I'd use it as a ZX81 emulator Stan? The idea of a "wolf in sheep's clothing" Pico 2 W in a ZX81 case, with a couple of USB slots and HDMI, stereo audio USB-C power, and a micro SD slot at the side rather appeals to me. Especially with a functional ZX81 membrane keyboard (you could always plug a USB keyboard in). If the ZX keyboard was only for decoration it wouldn't matter really, but it would be nice if it would do something. ---------- Although I like old computers I'm not one of those who sheds a tear over them. Face it, the hardware is junk by today's standards. The only reason to preserve old hardware is for compatibility with other hardware of the time. If you want to run CP/M then do it on modern, cheap, reliable hardware like a Pico. If you want to run a Speccy then use an emulator which will run far better than the original - and you can probably have disk storage thrown in for free. If you want a system with floppy disks then bt all means use a disk controller if you really must, but get a Gotek so you can have a pile of floppies on a USB stick. Much more reliable. :) (C64 masochists - please, learn to ignore that abortion of a BASIC and get something much better, like Sinclair BASIC. ;) ) The cases are iconic though. It would be sad if the only way to see them would be as fading photos in old magazines (or, of course, in scans of those magazines on a server somewhere). No-one can prepare you for the herculean task of lifting even an unequipped S-100 case onto the bench! Don't drop the mains transformer on your foot... Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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