Sinclair ZX80 / ZX81 / Z88 Forums

Make sure you keep us informed of your progress It will be fun!

So i got mine to work as well ! finally after all these years.
The printplate wasn't to good anymore, actually i think it wasn't ever to good to begin with. inefficient in it's layout and not the best quality, still if soldered once correctly it should be fine. I still have to add the transistor to RAMCS, but without it it works just fine as well, although i'm not sure what happens if you use 16K Ram.

Actually i started thinking about the RAMCS connection but then realized that it no effect once you plug in the 16K RAM extension, since then RAMCS is anyway high to disable the internal RAM, what should be done is disconnect MEMRQ to the back edge of the interface, and use a 7408 for that for instance. Anyway since it works as is i guess the whole thing is redundant although since i'm planning to build a 16-bit version i now plan to put that on the same print as the memory extension. (that should have emergency power i guess)

I propably told about this already:
http://www.microatena.it/scheda_libro.php?id=198&ord=N

On page 78 (it's page #88 on the PDF scan) there's an output-only very compact circuit reacting to pokes in the range 8192..16383.
That crazy guy suggested to ..SOLDER it over the Z80 CPU !!

My variant I used on a Spectrum had a less invasive EDGE connector. I used it a lot to drive 8 220 volt lights with TRIACs .. the Spectrum permits to write your own IM2 mode interrupt driver so the software could stay in sync with the lamps alternate current and avoid beating.
It was very good, actually, but it is difficult to show it.. the emulated version does not help either. But... wait ! could such "interface emulator" help you if we hook it to the EightyOne emulator ?

viewtopic.php?f=14&t=1486#p15607

i don't know about the emulators, ehm few things, - this is output only. that is a pity, - it seems to check if either pin A15 || A14 ||A13 is being written to, so if the address is below 16384, it is not a bad idea to use lower addresses but how would that work for input ? using a 74ls373 instead of the 74ls273 seems overkill, since this is the output bus the third state has no purpose, but works just as well. If i'm only using on/off i think i would use relays.

Well, I build my own interface from this book with 220v Light Bulbs in 1984.
I found the program on cassette and have rebuild it this month!
Thanks for PCB made it again with Adobe and a Chinese PCB maker.
If you have questions or like it, let me know via PM


IT STILL WORKS:

https://www.youtube.com/watch?v=BznpFw5 ... e=youtu.be

https://youtu.be/BznpFw5QmmU

Nice

Mark

Superblinkenlights! Nice work

Real Awesome!

Definitely a very nice I/O Board...I do ask tho' would this be for a single peripheral board to control
such as a AY3-8910,12,SPO256A-AL2 addon? I ask because I saw that has no expansion device select coding
for multiple add ons?