Search found 2441 matches

by 1024MAK
Sat Sep 21, 2019 1:03 am
Forum: Hardware
Topic: PRYNT, POKU, bad ROM or ULA in TS1000?
Replies: 7
Views: 133

Re: PRYNT, POKU, bad ROM or ULA in TS1000?

When I tap the PRINT key, I get "(PRYNT(" and when I use the POKE key I get "POKU." Have you folks ever seen this behavior? Which chips are in sockets? And have you tried removing them from their sockets, visually checking the chip pins for dirt or tarnish, and if clean/okay, putting the chips back...
by 1024MAK
Sat Sep 21, 2019 12:58 am
Forum: Hardware
Topic: PRYNT, POKU, bad ROM or ULA in TS1000?
Replies: 7
Views: 133

Re: PRYNT, POKU, bad ROM or ULA in TS1000?

TMAOne wrote:
Fri Sep 20, 2019 8:19 pm
See? There goes one now,...
If you get the correct time of year, wave a light around, and if you are lucky, you may see a flash of more than one at the same time. But be quick, or you may miss them... :mrgreen:

Mark
by 1024MAK
Thu Sep 19, 2019 3:40 pm
Forum: SALES
Topic: Lardo buys another zeddy
Replies: 13
Views: 483

Re: Lardo buys another zeddy

For U.K. subjects only: oh, look at how many U.S. dollars there were to Sterling back then... :( Back to the subject, have you peeked ( :lol: ) inside :?: If yes, does it use 4116 (or equivalent) DRAM chips? And can you post photos :mrgreen: Note I suspect there are four screws and two are hidden un...
by 1024MAK
Wed Sep 18, 2019 4:52 am
Forum: Hardware
Topic: Repairing lower RAM - which approach?
Replies: 6
Views: 169

Re: Repairing lower RAM - which approach?

Since the +5 powers the inverter for all other voltages, the +5 will always be on earlier than the others. If I understand the +12V regulation correctly, when it gets too high, it starts turning off TR5, which then turns off the inverter section. When the +12 then gets low enough, TR5 turns on agai...
by 1024MAK
Tue Sep 17, 2019 4:22 pm
Forum: Hardware
Topic: Repairing lower RAM - which approach?
Replies: 6
Views: 169

Re: Repairing lower RAM - which approach?

I have managed to find dodgy lower RAM by piggybacking a working chip on top of the each one in turn until it works. I literally just pushed the good chip on top of the soldered in chips. I don’t recommend this method unless you cut the output pin of the suspect DRAM chip. There are too many DRAM c...
by 1024MAK
Tue Sep 17, 2019 4:17 pm
Forum: Hardware
Topic: Repairing lower RAM - which approach?
Replies: 6
Views: 169

Re: Repairing lower RAM - which approach?

The first thing to do is to sort out the +12V and the -5V power issues. When a 4116 DRAM (or equivalent) chip fails, often it draws excessive current from the +12V (this is the main supply for these chips). The -5V is a bias supply and the current from this supply should be low. This is assuming tha...
by 1024MAK
Mon Sep 16, 2019 4:37 pm
Forum: Software
Topic: Daft question about ZX81 software on the ZX80
Replies: 5
Views: 268

Re: Daft question about ZX81 software on the ZX80

The ZX80 cannot load ZX81 cassette files.
The ZX81 cannot load ZX80 cassette files.

And yes, the BASICs are different.

More technical details here

There are some ZX80 programs on Paul’s site here ;)

Mark
by 1024MAK
Sun Sep 08, 2019 7:28 pm
Forum: Hardware
Topic: ZX80 trouble shooting
Replies: 28
Views: 596

Re: ZX80 trouble shooting

Good to hear that your ZX80 is up and running again 👍 8-) :D

Mark
by 1024MAK
Sun Sep 08, 2019 11:36 am
Forum: Hardware
Topic: ZX80 trouble shooting
Replies: 28
Views: 596

Re: ZX80 trouble shooting

I recommend fitting turned pin sockets. It makes life a lot easier for the future.

Mark
by 1024MAK
Sat Sep 07, 2019 11:09 pm
Forum: Hardware
Topic: ZX80 trouble shooting
Replies: 28
Views: 596

Re: ZX80 trouble shooting

Hmm, I’m going to have to think about this.... :?

Mark