ZX81 ULA-in-a-CPLD

[fordp2002]

I might just add that I'm using retrotechie's Xilinix implementation and ported it over to the Atmel atf1504 plcc44. Well, I'm at a loss as to why it wont work in slow mode? Everything else including the tape load/save works perfectly, but only in fast mode.

cheers
commie

Did you get anywhere with your ATF1504 design. If you have I am interested in making a ZX81 PCB for it I could send you one if I get it done.

[Zxkim81]

This replacement ula will save the zx81 your work is brilliant
Someone has to follow up on your work with the view of marketing this replacement ula.

[Lardo Boffin]

I would certainly be in the market for several!

[McKlaud]

Unfortunately all pictures stored on PhotoBucket gone and no chance to see what was on them.

Anyway, one of my ZX81s is dead and I decided to recreate the RetroTechie's implementation using XC9572XL. The prototype PCB on a breadboard under 13MHz generator test is in full flesh on the attached photo.

[McKlaud]

Hi,

Still work in progress with porting the RetroTechie's implementation into XC9572XL, but small success achieved. The ULA mini board inside a real ZX81 hardware, the clock signals read from pin 6 of the CPU and the composite video output with a 75 Ohm load.

[gammaray]

Bravo!

[Andy Rea]

Whooey, congratulations...

[Lardo Boffin]

Cool!

[Andy Rea]

not to trying to put a damper on everyones projects, but i have also been tinkering away in the background and as they say small is beautiful...

2" x 0.7" so pretty much the same outline as the socket it fits into... NO Bells, No Whistles, No Gimmicks just a plain vanilla ULA plug in and go.






of course some components on backside also

[McKlaud]

Andy, I am glad reading your post. You are Master Yoda of ZX81 ULA, I am just newbie in this world. BTW Could you correct pictures, I can't see them.