Search found 51 matches

by albertusj
Wed Aug 07, 2019 4:27 pm
Forum: Hardware
Topic: ZX80 issue 2 kit does not start
Replies: 9
Views: 369

Re: ZX80 issue 2 kit does not start

yes, but try a 6.5536MHz crystal also.
by albertusj
Tue Aug 06, 2019 1:16 pm
Forum: Hardware
Topic: Harlequin ZX Spectrum
Replies: 3
Views: 394

Harlequin ZX Spectrum

Has anybody here built the Harlequin ZX Spectrum clone? Is it a very challenging project? Is the board through-hole plated and is it pretty much a case of work slowly and carefully, put everything in the right places and you'll be OK? If I choose the 128K version, will it be backwards compatible wit...
by albertusj
Tue Aug 06, 2019 12:09 pm
Forum: Hardware
Topic: Tape Loading
Replies: 4
Views: 229

Re: Tape Loading

I did an analysis of tape data storage here:

http://www.myprius.co.za/tape_storage.htm
by albertusj
Mon Aug 05, 2019 3:06 pm
Forum: Hardware
Topic: ZX80 issue 2 kit does not start
Replies: 9
Views: 369

Re: ZX80 issue 2 kit does not start

I just built one of these:

http://www.myprius.co.za/ZX80.htm

No transistor buffer was necessary, only a back-porch generator. The kit I bought had the WRONG frequency resonator. I had to put in a 6.5536MHz crystal myself.
by albertusj
Sun Jul 28, 2019 12:45 pm
Forum: SALES
Topic: ZX Spectrum Issue 2
Replies: 3
Views: 398

Re: ZX Spectrum Issue 2

will do
by albertusj
Sat Jul 27, 2019 11:45 am
Forum: SALES
Topic: ZX Spectrum Issue 2
Replies: 3
Views: 398

ZX Spectrum Issue 2

I have a ZX Spectrum issue 2 board in need of restoration/repair. It doesn't boot, but it does produce a video signal albeit a distorted one. When I put the ULA from an Issue 4 in the motherboard it showed a 1982 Sinclair Research, but the video was still distorted. I checked every chip has power. M...
by albertusj
Sun Jul 21, 2019 6:33 pm
Forum: Hardware
Topic: ZX80 from NTSC to PAL?
Replies: 11
Views: 444

Re: ZX80 from NTSC to PAL?

It's probably not even interlaced so at 50Hz display you're only looking at ~312 lines progressive scan.
by albertusj
Sat Jul 20, 2019 11:15 am
Forum: SALES
Topic: QL Programming and how-to Books
Replies: 0
Views: 192

QL Programming and how-to Books

I'm selling a number of QL books:

https://www.ebay.com/itm/223594232125
by albertusj
Thu Jul 18, 2019 11:14 am
Forum: Hardware
Topic: 2732 to 2532 adaptation
Replies: 8
Views: 363

Re: 2732 to 2532 adaptation

Thanks 1024!
by albertusj
Wed Jul 17, 2019 5:54 pm
Forum: Hardware
Topic: 2732 to 2532 adaptation
Replies: 8
Views: 363

Re: 2732 to 2532 adaptation

On the board, which enable pin is actively used, pin 18 or pin 20 on the 2732? Or are both used? Only, some ROM chips and the 2532 only have one enable pin. And yes, the A11 line needs swapping. Connect VPP to +5V. Mark PIN 18 on 2732 is actively used. So what shall I do with GVpp on the 2732? It c...