Search found 18 matches

by overCLK
Fri Nov 09, 2018 12:58 am
Forum: Welcome Area
Topic: Hello from Spain
Replies: 9
Views: 4446

Re: Hello from Spain

McKlaud wrote: Fri Nov 09, 2018 12:17 amhi Manuel :)
Hi Claudius. Thanks for dropping by. ;-)
by overCLK
Fri Nov 09, 2018 12:57 am
Forum: Welcome Area
Topic: Hello from Spain
Replies: 9
Views: 4446

Re: Hello from Spain

Hola Manuel :P Around you you should also find some interesting stuff as for Indescomp wich made many things in Spain for the ZX (memory extension, keyboard case, FDD controler, HRG and sound cards, many programs too, ...) I had the chance to buy /exchange some Indescomp products in France in the 8...
by overCLK
Fri Nov 09, 2018 12:50 am
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 238
Views: 123498

Re: ZX81 ULA-in-a-CPLD

Following Alvin's documents 1/ Hsync generation is shown below. 2/ Regarding NMI generation Next to it 2 flip-flops that control the software-generated vertical sync, and whether the Z80 receives NMI's. A high input on "zx80_zx81" lets NMI's pass through as in a ZX81, a low input disables NMI's as ...
by overCLK
Fri Nov 09, 2018 12:42 am
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 238
Views: 123498

Re: ZX81 ULA-in-a-CPLD

Great stuff... so assuming it's not a hardware problem / bad connection, missed pull up resistor ect... Hi Andy. Thanks a lot for your feedback. Congratulations on your awesome implementation. I checked twice all the connections and even built two units to check consistent failure. :-) Regarding pu...
by overCLK
Fri Nov 09, 2018 12:22 am
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 238
Views: 123498

Re: ZX81 ULA-in-a-CPLD

Hi Manuel, Congratulation with your works. To be honest I stopped at the same point where you are now (issues with the NMI gen). ZX80 mode works fine, loading form tapes is good, it works fine with ZXpand+. I’ve shelved the zULA project for a while and learned a bit about CPLDS. I’ve promised mysel...
by overCLK
Thu Nov 08, 2018 7:34 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 238
Views: 123498

Re: ZX81 ULA-in-a-CPLD

Hello all. I was really glad to know that finally there are some ULA replacement on modern comodity hardware. Congratulations to the winners! :-) Half a year ago my only working ZX81 started to show a strange behaviour, some missing pixels always in the same position and also the printed characters ...
by overCLK
Thu Nov 08, 2018 10:22 am
Forum: Welcome Area
Topic: Hello from Spain
Replies: 9
Views: 4446

Re: Hello from Spain

Hello overCLK A warm welcome to our forum. I’m glad to hear that you have got one of your Zeddies working :D Please do enjoy the forum. When he has recovered, Andy (a member here) may make some more of his replacement ULA modules. For more information have a read of this thread ;) Mark Hi Mark. Tha...
by overCLK
Wed Nov 07, 2018 11:20 pm
Forum: Welcome Area
Topic: Hello from Spain
Replies: 9
Views: 4446

Hello from Spain

Hello all! Just joined and wanted to introduce myself :-) My name is Manuel and live in the northwest of Spain (yes, the green and rainy side). I've found this forum to be an awesome source of information since I've got two ZX81 computers about a year ago. I bought them untested and had luck with on...