Re: [neonixie-l] ZX81 Nixie Clock

Michel van der Meij Tue, 23 Apr 2013 15:14:50 -0700

It's a bit more difficult to turn a ZX80 into a nixie clock as it doesn't have a NMI circuit (you can add that by using a ZX80 to ZX81 conversion). The NMI is used to build up the screen in SLOW mode (ZX80 doesn't have SLOW mode) and this interrupt vector can be re-directed to your own interrupt routine to run a clock routine.

Alternatively, you can generate a 2Hz NMI with external parts but you would have to patch the ROM as there is probably no NMI interrupt vector set.

You can find all the details here:
http://searle.hostei.com/grant/zx80/zx80nmi.html

Michel

on Apr 24, 2013, threeneurons <[email protected]> wrote:

That's a beauty ! I've got an old Sinclair ZX80 stashed away. Its the white bodied one that, I think, precedes this one. I'll have to dig it out, and see what I can do with it.

On Monday, April 22, 2013 12:14:55 AM UTC-7, Michel wrote:
After cleaning out the garage a few weeks ago and stumbling across my

good old ZX81 (well, TS1000 really), I thought it would be quite

interesting to turn it into a Nixie Clock!

Here's the result:

http://xiac.com/Images/ZX81NIXIECLOCK.jpg

I designed it with TTL logic, no SMD components here. It is direct

drive using 4 K155ID4 drivers.

If there is enough interest, I will offer this clock as a kit.

Michel

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Re: [neonixie-l] ZX81 Nixie Clock

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