Quick and dirty RAM test for CPC

[LambdaMikel]

The last Picture above is very similar to a fault i just fixed (on a 464).

Hi AUdronic, I think there is a missunderstanding. This picture shows the perfectly fine working CPC 6128 which I am using to flash the XMem with the ramtest.bin lower rom... this is the picture that I am getting when I am booting ramtest.bin lower rom from the XMem on this 6128. Is the memtest not compatible the 6128? So my intent is of course to use the XMem with the memtest.bin lower rom in the broken 464 of course. Clear now?

[LambdaMikel]

OK, figured it out by now... it was my DSK / HFE image creation process which was bad.
Was able to flash and run it  now - thanks to all who helped!

Unfortunately, I am seeing a lot of red... probably not a good sign, uhh? 

[Audronic]

@LambdaMikel
Perhaps Just replace 1 (One) memory chip and re run the RamTest.
All Faulty ??


Good luck


Ray

[LambdaMikel]

Hi Ray,
which one should I replace first?

Michael

[Audronic]

Hi Ray,
which one should I replace first?
Michael

I don't think it matters as we want to see GREEN on the RamTest.
Please put a socket in as well.


Ray

[LambdaMikel]

AH, I see. So you are trying to figure out if replacing the RAM chip makes a difference at all.
Maybe some other components got burned as well. That's a good strategy.

Now where would I get RAM chips... hmmm. Will look on Ebay.

[GUNHED]

which one should I replace first?

The one which becomes warm at first, but looking at the picture, probably 2 chips are bad. Ask Gerald, he is the expert. 

[Bryce]

The one which becomes warm at first, but looking at the picture, probably 2 chips are bad. Ask Gerald, he is the expert. 

Actually the picture would suggest that all 8 RAM chips are bad which is quite unlikely, hence the "replace one to see if a green line appears" suggestion is a good idea. I also think that it's something other than the RAM, possibly one of the RAM buffer chips (74LS244 and 74LS373) or maybe just the enable signal to these (from the GA)?

Bryce.

[LambdaMikel]

Actually the picture would suggest that all 8 RAM chips are bad which is quite unlikely

But remember, I fried the whole thing with 12 Volts... for a couple of seconds before I noticed it.

[gerald]

OK, figured it out by now... it was my DSK / HFE image creation process which was bad.
Was able to flash and run it  now - thanks to all who helped!

Unfortunately, I am seeing a lot of red... probably not a good sign, uhh? 

Too much red to my taste.
While you could end with most bit at 1 with failing RAM (all 1 will give the red), I am worried that the pattern changes exactly when the border changes.
Any chance you can check the Gate Array in an other CPC ?

[LambdaMikel]

Any chance you can check the Gate Array in an other CPC ?

I am afraid this is my only 40010 CPC - my other CPCs have 40007 and 40008.

[LambdaMikel]

The board has a spare "socket" for the 40007 / 40008 Gate Arrays though. If it should turn out that the 40100 is defect, it could be replaced with 07 or 08... has anybody tried that before?


This is my board
http://www.cpcwiki.eu/index.php/File:CPC464_Z70200_MC0008C_PCB_Top.jpg


I am not sure I can spend so much time desoldering all the RAMs and then also to put in another Gate Array.


Awesome RAM test though, Gerald! 

[LambdaMikel]

    Any chance you can check the Gate Array in an other CPC ? I am afraid this is my only 40010 CPC - my other CPCs have 40007 and

Surprisingly, the 40010 is OK! Tested it in my CPC 6128 

[LambdaMikel]

My RAM arrived and it is almost working... however, RAMTEST still shows a red bar in the border.
What does that mean? Now more "grizzle snow" on the screen though, I suppose that is a good sign?

[LambdaMikel]

Missed some more tracks! Fixed now, thanks to all who helped!
You guys rock!! 

[robcfg]

Cool! So glad you could get it running again!

[VincentGR]

Another one saved!!!
Congratz 

[00WReX]

The thrill you get when it springs back to life is very cool, I'm sure you just experienced that feeling.
Congratulations on working through it. 

And yet again, another big shout out to Geralds 'famous' RAMtest. 

Cheers,
Shane

[LambdaMikel]

The thrill you get when it springs back to life is very cool, I'm sure you just experienced that feeling. Congratulations on working through it.  And yet again, another big shout out to Geralds 'famous' RAMtest. 

Ineed, a marvelous feeling it is! I was like "yeaaah" 

Without RAMTEST I probably wouldn't have started the repair - the group's good support was also essential.

[DanyPPC]

Really great tool to test ram on our machines !

[llopis]

Does someone know if you can use this RAM test with ROMBO, or is it just with something like X-MEM?
I'm asking because I got my ROMBO sooner than X-MEM, and while I'm able to load all sorts of other ROMs, this one just brings up the boot text with the blue background, puts a few garbage pixels on screen and freezes. I even tried it in slot 0 just in case, but that causes a constant reboot.
Any suggestions?

[Bryce]

There are essentially two ROM0's in a CPC. The LowerROM (Firmware) and UpperROM (BASIC). This ROM needs to be mapped to the LowerROM area, so ROMBO can't be used as it can only replace the Upper portion of ROM 0.

Bryce.

[rpalmer]

While bryce is correct that the current rombo cannot replace the internal lower rom. A modification to it can replace the internal ROM 0 (both upper and lower).
This would achieved by:
a. Detecting ROM 0 as being the current ROM being addressed (either upper and lower).b. Detecting that the ROMEN signal is active.c. Finally inserting your own ROMDIS signal (from the expansion bus) to the internal ROM when A15 is also low and in parallel engaging the external ROM 0 (for lower half).
rpalmer

[llopis]

There are essentially two ROM0's in a CPC. The LowerROM (Firmware) and UpperROM (BASIC). This ROM needs to be mapped to the LowerROM area, so ROMBO can't be used as it can only replace the Upper portion of ROM 0.

Thanks, that's what I figured, but I wasn't able to confirm it anywhere. I'll just keep waiting for X-MEM to arrive :-)

[jonnixx]

Hi,


I have two problems.
The CPC 6128 with standard RAM.
Original problem:
If the machine is cold (room temperature) then i can load the R-type Reloaded from floppy (3") and HxC and run the program.
... and then not cold the machine (after 3-4 minutes) press reset and can not load the game. (Freeze the program during loading)


Second problem:
The dirty ram test is failed. (attached picture)


I have replaced:
- 8 RAM modules (new rams: TMS4164-12NL)
- 74LS244 and 74LS373
Could you please help me?


Jonni

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