Sinclair ZX80 / ZX81 / Z88 Forums

landex wrote: ↑Sun May 29, 2022 8:43 pm My has more 2x4164 chips

From what I understand, something like a Retroleum Smart card in diagnostic mode would be able to check the ram chips, I can't check this myself because my TC2048 doesn't boot up for some reason.

Unless you can desolder the chips and test them, relying upon the compatibility with a standard Spectrum rom to run one of the Spectrum diagnostic roms in a expansion would be your best bet.

My TC may have a faulty rom, it uses a 27128 not a 23 series. I've tested my ram chips and they work.

sP1d3r wrote: ↑Sun May 29, 2022 11:36 pm
From what I understand, something like a Retroleum Smart card in diagnostic mode would be able to check the ram chips,

I don't know if the Retroleum Smart card would help because I have a dandanator and it doesn't work in tc2048. It should, shouldn't? at least the 16k games.

landex wrote: ↑Mon May 30, 2022 1:01 am
I don't know if the Retroleum Smart card would help because I have a dandanator and it doesn't work in tc2048. It should, shouldn't? at least the 16k games.

I know that there's very little difference between a TC2048 rom and the Spectrum rom, see;

https://timex.comboios.info/tc2048.html

so perhaps it should.

Thanks guys! At least I have an 16k TC2048

By the way, what s happen if I remove all hi-mem? Isn't the same as 16k?

landex wrote: ↑Mon May 30, 2022 6:43 pm
By the way, what s happen if I remove all hi-mem? Isn't the same as 16k?

Which chips are which?

sP1d3r wrote: ↑Mon May 30, 2022 10:10 pm

landex wrote: ↑Mon May 30, 2022 6:43 pm
By the way, what s happen if I remove all hi-mem? Isn't the same as 16k?

Which chips are which?

U8, U9, U10, U11

sP1d3r wrote: ↑Sun May 29, 2022 3:44 pm

landex wrote: ↑Sat May 28, 2022 4:23 pm Can it be a memory chip?

A Timex TC2048 has two different types of memory chip, two 4416 and two 4164 chips, IIRC.
The thing to do would be to desolder and test the chips with a DRAM tester, this would eliminate the memory chips as the source of the problem.

I believe there were at least two different boards made, each using different DRAM chip arrangements.

landex wrote: ↑Mon May 30, 2022 1:01 am

sP1d3r wrote: ↑Sun May 29, 2022 11:36 pm
From what I understand, something like a Retroleum Smart card in diagnostic mode would be able to check the ram chips,

I don't know if the Retroleum Smart card would help because I have a dandanator and it doesn't work in tc2048. It should, shouldn't? at least the 16k games.

Did you try the second program I posted? What were the results?
If it’s working enough for BASIC to run, it’s possible to do plenty of useful tests just using BASIC.

Mark

Mark, I put the 2nd program and it's strange. The output is the same. Example:
Memory 44000. Output always 3.
Also 35000, output 3 all.
Adresse 12, all 95.
Adresse 7800, all 10.

What can it be now?

Last two addresses are in ROM.
Try 32760 to 32780

Paul wrote: ↑Tue May 31, 2022 5:42 pm Last two addresses are in ROM.
Try 32760 to 32780

Hi Paul.
I try it
From 32760 to 32767 it's everything ok. But from 32768 to32780 it adds 1 value at 0, 85 and 170. The 255 it's in every memory fine.

32767 it's the last memory of the 16kb, isn't?