wow! what a great build considering the time you made this and your age. the way you've used old pencil cases and cut keycap info out of magazines is so creative. it reminds me of being a kid myself, even though i never made anything as complex, there was a great make do and mend attitude around that time. i often made artwork using old cereal boxes and cut outs from magazines.. it's sad that it's not like that anymore.
Thanks! I recall it was a fun build and made using the ZX81 so much easier afterwards. I'm actually planning on prototyping a Q68 build out of cardboard first just to see if I can get the look I want. I have a 60% keyboard that will go into a very small compartment and to the side of it will go the small fpga-based motherboard...that's on the agenda.
Thank you. Yes, you had to be very creative. The one pro though was that Radio Shack back then was really a great resource for both material and expertise. I used to love going into a store and talk to the techies...they were more that than sales people.
Thumbs up and subscribed. Looks like a TI-99 4A Mitsumi keyboard, Radio Shack sold these in plastic bags in mid-to-late 80s. I'm not a fan of the Sinclair computers, but I respect your retro technical skills. Good channel.
Oh cool, I thought I recall it being TI-99 4A based one. I seem to recall getting it second-hand...maybe it was in a Radio Shack bin of mark-downs/returns.
If I had done something like this 35 years ago I would remember it. Maybe not in detail. But I would remember most of it when I saw it. I think it's funny
I know, over 35 years ago is a long time. I knew I had it but couldn't find it for a while. I completely forgot why I added the amp. I did another video coming out in the future that explains why--if you watch the previous video (a short 30 second clip) it explains why...to allow for digitized speech to play and be heard clearly.
Nice one, love that DIY keyboard. Regarding the issue with it not booting without the rampack installed. I think the onboard 1k ram chip is bad, the way the ZX81 works is that when you plug in the rampack it disables the onboard 1k ram hence allowing the computer to boot. as for crashing after its been on a while, try changing the 7805 voltage regulator or better still replace it with one of the modern replacements based on a DC-DC converter. They don't produce the heat the old linear regulates like the 7805 do. Also well worth checking the electrolytic capacitors in the ZX81 (Think there are only two or three) but also in the 16K rampack, Most of the ZX81 rampacks I've encountered use eight 4116 ram IC's that need three different voltages to operate, these are created inside the rampack using a DC-DC converter circuit and that has some electrolytic capacitors that when they start to age can cause the problems you seem to be having.
I'll have to take a look at it again. If the RAM is broken, I bet it was broken even back when I used it regularly since I don't think I ever much used it without the 16K RAM pack back then.
wow! what a great build considering the time you made this and your age. the way you've used old pencil cases and cut keycap info out of magazines is so creative. it reminds me of being a kid myself, even though i never made anything as complex, there was a great make do and mend attitude around that time. i often made artwork using old cereal boxes and cut outs from magazines.. it's sad that it's not like that anymore.
Thanks! I recall it was a fun build and made using the ZX81 so much easier afterwards. I'm actually planning on prototyping a Q68 build out of cardboard first just to see if I can get the look I want. I have a 60% keyboard that will go into a very small compartment and to the side of it will go the small fpga-based motherboard...that's on the agenda.
@@8BitRetroJournal sounds great.. can't wait to see how it turns out
It is great! Building your own electronics project back in the 80s was so hard I think. :)
Thank you. Yes, you had to be very creative. The one pro though was that Radio Shack back then was really a great resource for both material and expertise. I used to love going into a store and talk to the techies...they were more that than sales people.
Thumbs up and subscribed. Looks like a TI-99 4A Mitsumi keyboard, Radio Shack sold these in plastic bags in mid-to-late 80s. I'm not a fan of the Sinclair computers, but I respect your retro technical skills. Good channel.
Oh cool, I thought I recall it being TI-99 4A based one. I seem to recall getting it second-hand...maybe it was in a Radio Shack bin of mark-downs/returns.
If I had done something like this 35 years ago I would remember it. Maybe not in detail. But I would remember most of it when I saw it. I think it's funny
I know, over 35 years ago is a long time. I knew I had it but couldn't find it for a while. I completely forgot why I added the amp. I did another video coming out in the future that explains why--if you watch the previous video (a short 30 second clip) it explains why...to allow for digitized speech to play and be heard clearly.
Amazing, I can imagine the excitement you had building this wonderful machine. Beautifully engineered!
Wow, great work, very impressed
Elite for the ZX81? You should definitely make an episode about that.
That's a great idea...going to put that on my list for February or April (March is a themed month for the Mac which I want to participate in).
Nice one, love that DIY keyboard. Regarding the issue with it not booting without the rampack installed. I think the onboard 1k ram chip is bad, the way the ZX81 works is that when you plug in the rampack it disables the onboard 1k ram hence allowing the computer to boot. as for crashing after its been on a while, try changing the 7805 voltage regulator or better still replace it with one of the modern replacements based on a DC-DC converter. They don't produce the heat the old linear regulates like the 7805 do. Also well worth checking the electrolytic capacitors in the ZX81 (Think there are only two or three) but also in the 16K rampack, Most of the ZX81 rampacks I've encountered use eight 4116 ram IC's that need three different voltages to operate, these are created inside the rampack using a DC-DC converter circuit and that has some electrolytic capacitors that when they start to age can cause the problems you seem to be having.
I'll have to take a look at it again. If the RAM is broken, I bet it was broken even back when I used it regularly since I don't think I ever much used it without the 16K RAM pack back then.
Nice, I am curious about that speaker and wat you had it connected to on the ZX81
i was playing around with the speech synthesis software back then.
@@8BitRetroJournal Ah, so its an amp connected to the zx81 audio out and you were hearing digitised sound...
@@vectrexmad Yup...I actually forgot myself until, months later, i found my synthesis program and played with it.
Had to allow an update to install should have been able to write a shell script to update automatically but no go.
Since it works with the RAM pack and does not with only internal RAM, the pretty ceramic RAM chip inside is failing, or maybe its socket has corroded.
Thanks, I'll try and unseat it and check.