Search found 12 matches

by GTS1000TX
Sun Apr 19, 2020 5:58 am
Forum: Hardware
Topic: Zx-81 clock question.
Replies: 2
Views: 1183

Re: Zx-81 clock question.

Thank you for the information.
by GTS1000TX
Fri Apr 17, 2020 12:17 am
Forum: Hardware
Topic: Timex Sinclair 1000 displaying wrong character.
Replies: 8
Views: 2535

Re: Timex Sinclair 1000 displaying wrong character.

My RAM arrived. And as everyone suspected, it didn't resolve the issue. I don't see any solder beads or broken traces. Except for the RAM, I removed the chips one at a time to inspect under them.I didn't see anything suspicious. I guess my next option is wait for the ULA replacement to become availa...
by GTS1000TX
Thu Apr 16, 2020 8:47 pm
Forum: Hardware
Topic: Timex Sinclair 1000 displaying wrong character.
Replies: 8
Views: 2535

Re: Timex Sinclair 1000 displaying wrong character.

Thanks for the info. The ROM isn't an EProm. No jumper wires.
by GTS1000TX
Wed Apr 15, 2020 5:20 pm
Forum: Welcome Area
Topic: Hello from Fort Worth, TX
Replies: 7
Views: 5441

Re: Hello from Fort Worth, TX

Thanks again. I'll look around on the board for broken traces or solder beads. Fortunately the chip is in a socket. I wish the RAM was to. It's the only one not in a socket. I assume if the ROM was not on the correct pins in its 28 pin socket, I wouldn't get anything on the screen.
by GTS1000TX
Wed Apr 15, 2020 1:49 pm
Forum: Hardware
Topic: Zx-81 clock question.
Replies: 2
Views: 1183

Zx-81 clock question.

After reading this post https://sinclairzxworld.com/viewtopic.php?f=7&t=1851 I saw the clock pulse feeding into the Z80A is out of phase with the one coming from the ULA. I read these articles http://www.worldofspectrum.org/hardware/rep3.html , but did not see an explanation. I thought they would be...
by GTS1000TX
Wed Apr 15, 2020 2:00 am
Forum: Welcome Area
Topic: Hello from Fort Worth, TX
Replies: 7
Views: 5441

Re: Hello from Fort Worth, TX

Thanks. I was afraid it would be the ULA. And who know's what other problems it may have. Since they're all out of stock, my options are limited. I saw in the Hardware board someone created a new board called the ZX81+38. I've been wanting to build my own computer. And that one may be affordable. An...
by GTS1000TX
Wed Apr 15, 2020 12:31 am
Forum: Hardware
Topic: Timex Sinclair 1000 displaying wrong character.
Replies: 8
Views: 2535

Re: Timex Sinclair 1000 displaying wrong character.

I saw in this 2016 post viewtopic.php?f=7&t=1851, that there's a ULA replacement called Andy's ULA. Most of the info I found shows it began in 2008. I'm not sure where to get one.
by GTS1000TX
Tue Apr 14, 2020 2:19 pm
Forum: Hardware
Topic: I started on my new ZX-81 replacement board (kit) ZX81+38
Replies: 60
Views: 48047

Re: I started on my new ZX-81 replacement board (kit) ZX81+38

This looks very cool. Some Atari folks designed new boards for Its 8bit line. I wanted to build one, but could not justify the expense. Was going to be over $500 to build one myself. The wife would kill me. But this appears more affordable. And I just happen to have a Timex Sinclair 1000 that may ha...
by GTS1000TX
Tue Apr 14, 2020 2:16 pm
Forum: Hardware
Topic: Timex Sinclair 1000 displaying wrong character.
Replies: 8
Views: 2535

Timex Sinclair 1000 displaying wrong character.

Originally I posted this in the welcome forum last year. I followed up a few days ago because I finally had time to work on it again. Last year, I bought a Timex Sinclair on eBay which appears to have never been used. The picture was terrible via RF on a modern LCD display. But I could see the K. Wh...
by GTS1000TX
Mon Apr 13, 2020 8:27 pm
Forum: Hardware
Topic: ZX81 grey vertical lines on screen
Replies: 14
Views: 5248

Re: ZX81 grey vertical lines on screen

Mind if I tag along? Yesterday, I did the transistor and 2 resistor composite mod on my TS1000. And it has the same vertical gray bars. It has the 2C210E ULA. I'm connected to an LCD display via composite. Looks much better than RF could produce. I think RF had them too. But the picture was very poo...