Timex Sinclair 1000 repair

[Chris Savage]

One i know of was ZX81 +38 or something like that

I was going to order this one, but as you can see, shipping to the U.S. starts at $50.00!!!

[JKnightandKARR]

One i know of was ZX81 +38 or something like that

I was going to order this one, but as you can see, shipping to the U.S. starts at $50.00!!!

Order that with the sockets for the chips! Only an additional $50.... lol kinda $$$$$$ can buy an original for 1/4 cost

[JKnightandKARR]

One i know of was ZX81 +38 or something like that

I was going to order this one, but as you can see, shipping to the U.S. starts at $50.00!!!

https://github.com/mahjongg2
I found this, idk if this looks interesting to you or not, beats $250... lol

Edit: Here's what looks like original PCB of the ZX-81
https://github.com/Bluescreen2001/ZX81-PCB/tree/main/ZX81_keyboard

[granz]

Also, related to this: Brian (AKA @MicroNut) has (had?) a ZX-81 remake.

Define: remake?

A modern remake of the old ZX-81. There are several (one of them is here: https://www.hackup.net/2022/01/building-a-new-zx81-computer/.) I don't remember which one Brian had, as that show was many years ago. That is why I tagged Brian, I was hoping that he could pitch in.

[Chris Savage]

Order that with the sockets for the chips! Only an additional $50.... lol kinda $$$$$$ can buy an original for 1/4 cost

Yeah, I did think the $50.00 for extra sockets was a bit much. Of course, the modernized versions don't require an old TV to get video.

[Chris Savage]

A modern remake of the old ZX-81. There are several (one of them is here:

I don't think tagging works on SMF.    That PCB looks like the one JKnightandKARR linked. Mahjongg?

[MicroNut]

The remake that Granz was mentioning that I had was a DE0-Nano FPGA board with a ZX81 softcore called ZXGate I found on the internet. The "cassette" was an Arduino Due which had a TFT screen and a SD card reader. Sadly I lost the code for the Arduino but I also made a "cassette" with a Propeller 1, SD card reader and a serial 16x2 LCD. I no longer have that code either.

The cassette remake is just reading an SD card and then bit banging pulses based on each bit of each byte. Once the timing is determined and using a 3.3V output you can feed it into the "mic" jack. It wouldn't be too hard to replicate it again and I found that it is more reliable than the actual cassette system.

I also have 2 TS1000s, a US ZX81 and the ZXMore kit (can also do ZX80) that is no longer available.

[granz]

Thanks Brian, I was pretty sure (>99%) that you had a TS-1000 clone, but I forgot that it was an FPGA system. I also think that I have a DE-0 system somewhere, that I inherited when Peter moved out.

By the way - did you get an email alert from my tagging you, or did you just happen to log in and see the posts?

[JKnightandKARR]

Order that with the sockets for the chips! Only an additional $50.... lol kinda $$$$$$ can buy an original for 1/4 cost

Yeah, I did think the $50.00 for extra sockets was a bit much. Of course, the modernized versions don't require an old TV to get video.

Just alittle bit... lol

The remake that Granz was mentioning that I had was a DE0-Nano FPGA board with a ZX81 softcore called ZXGate I found on the internet. The "cassette" was an Arduino Due which had a TFT screen and a SD card reader. Sadly I lost the code for the Arduino but I also made a "cassette" with a Propeller 1, SD card reader and a serial 16x2 LCD. I no longer have that code either.

The cassette remake is just reading an SD card and then bit banging pulses based on each bit of each byte. Once the timing is determined and using a 3.3V output you can feed it into the "mic" jack. It wouldn't be too hard to replicate it again and I found that it is more reliable than the actual cassette system.

I also have 2 TS1000s, a US ZX81 and the ZXMore kit (can also do ZX80) that is no longer available.

That'd be VERY handy! I'd like one if one can be recreated.

A modern remake of the old ZX-81. There are several (one of them is here:

I don't think tagging works on SMF.    That PCB looks like the one JKnightandKARR linked. Mahjongg?

Did you see the files I posted? I think original PCB designs, as well as new designs as you already saw,  for the ZX=81 or Timex Sinclair 1000, seem that the 2 systems, even though technically the same, are somewhat different, at least as far as the RF boxes are concerned.

[MicroNut]

Granz, no I didn't see the alert.

JKKnightandCARR - sadly I lost all my ZX81 FPGA and Cassette source code when the external hard drive I had it on went bad. I do have the ZX-gate source though which is good since it is no longer on the net.

I'm thinking of redoing it. I know the ZX-Gate used a PS2 Keyboard and VGA output. When I used the DE0-Nano I tapped into the video output before the vga conversion and had to use a transistor driver to get the composite output. I now have a DE10-Lite which has a built in VGA and Arduino header with double the space of the Nano so I will do it on that instead. Once that is done it'll be easy to port it over to the Nano

I'll start a thread on the Projects category when I get it going so I won't hijack this thread.

[Chris Savage]

Granz, no I didn't see the alert.

I've looked into mods for SMF that can do this, but the few I see don't look like they've been updated in years.

EDIT: Ironically, the manual says they're supported. I need to check on permissions. I will look into this now.

[JKnightandKARR]

@Chris Savage
I think I gotta place to start. Posted on the Vintage Computer Forum and was told to check Reset (Pin 26) which is active low, so 0v is expected. at the card edge connector, I am getting 5v, so here's the place to start I think.

[granz]

@Chris Savage
I think I gotta place to start. Posted on the Vintage Computer Forum and was told to check Reset (Pin 26) which is active low, so 0v is expected. at the card edge connector, I am getting 5v, so here's the place to start I think.

Reset is, as you mentioned, an active low signal. That means that when it is reading 0V, the CPU is in reset condition. When Reset is +5V, then the CPU is not in reset, and should be running properly.

[JKnightandKARR]

@Chris Savage
I think I gotta place to start. Posted on the Vintage Computer Forum and was told to check Reset (Pin 26) which is active low, so 0v is expected. at the card edge connector, I am getting 5v, so here's the place to start I think.

Reset is, as you mentioned, an active low signal. That means that when it is reading 0V, the CPU is in reset condition. When Reset is +5V, then the CPU is not in reset, and should be running properly.

Ok, the VCF forums said it should be low. Probly replace all caps n go from there...

[Chris Savage]

Ok, the VCF forums said it should be low. Probly replace all caps n go from there...

The VCF forums said the /RESET line should be LOW normally? That is incorrect. It should only be LOW for like a millisecond at power-up. After that it should remain HIGH. And it must be, since you already confirmed that the /M1 line was changing states, which indicates the Z80 is executing instructions. It couldn't do that if /RESET was LOW.