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Re: ZX81 ULA-in-a-CPLD

Posted: Tue Aug 15, 2017 2:53 pm
by fordp2002
commie wrote:
Sat Nov 19, 2016 10:09 pm
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.

Re: ZX81 ULA-in-a-CPLD

Posted: Sun Dec 24, 2017 5:44 pm
by 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.

Re: ZX81 ULA-in-a-CPLD

Posted: Sun Dec 24, 2017 8:50 pm
by Lardo Boffin
I would certainly be in the market for several!

Re: ZX81 ULA-in-a-CPLD

Posted: Tue Jan 23, 2018 9:48 pm
by 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.

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 1:46 am
by 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.

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 2:57 pm
by gammaray
Bravo!

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 3:19 pm
by Andy Rea
Whooey, congratulations...

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 9:57 pm
by Lardo Boffin
Cool!

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 10:40 pm
by 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.

Image
Image
Image


of course some components on backside also

Re: ZX81 ULA-in-a-CPLD

Posted: Fri Mar 09, 2018 11:54 pm
by 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.