SOLVED trump-card V1 filled with ram chips only sees 256 kb

[techy]

Hi forum ,


What am i overseeing here ??

card is filled with 41256 chips ,

But only reports 256kb

firmware is version 1.21a , tried it with 1.37 same result , pal's seem original

is there a pal difference between 256 , and full version ?

plugged in only reveals 256k ( no other cards )

[Pr0f]

There's no specific PAL for 768K versus 256K - it really is just a matter of populating the sockets.

I originally had a 256K card which I upgraded to 768K.

Are there other interfaces plugged in as well?

[RalfR]

Are there other interfaces plugged in as well?

( no other cards )

[techy]

Is there a schematic anywere ?

so the ql is booting as it should , no errors , no strangies on the screen .

but it looks like the trumpcard is not recognizing 2 memory banks at all

[RalfR]

Is there a schematic anywere ?

Look here: viewtopic.php?t=1486

[techy]

mine is a trumpcard version 1 , with 24 memory chips

[Derek_Stewart]

Hi

I have 3 v1 Trump Cards, they all use 41256 ram chips.

The configuration should be 3 banks of 8 x 256K 8 bit chips.

So: 256/8 = 32K per chip x 8 chip gives 256K per ram bank.

3 ram banks give 768K

Maybe there are some faulty ram chips. Which might switch off the ram bank in the memory scan. Try testing the ram chips.

[aalea]

If I need to test this card, I will do this test, at least to got a better idea of what happend.

I will check socket and pins of 2V2 PAL, the only diference in pins between all memory chips are the RAS pin provided by this chip that is diferent in each bank, a bad solder, or broken pin will cause you only see 256Kb.

Next I remove all chip memory and try 8 of each time, with a minerva rom (because it check RAM and inform of faulty chips), I do not know what bank is the first one, top of botton, you should check.
If All chips work, I will try using only 2 banks to try to get a total 640Kb.

With this you can ensure that all chips are OK, and that are not interfering ones with others.

Next I will check the two diodes near the ¿74LS245? on the corner of the card, can affect, but I think will do a different error.

And last, in you picture, the 74LS04 near de crystal is in a socket, but not other chips, I suspect that a repair was done around this chip, so I will check again (but I think this shall do a different error).

Is the disc drive working properly? (This is only a clue that a part of the circuit is working ok, we already know that ROM and PAL 1 shall be working OK).

[tofro]

Why don't you start with removing one bank at a time to find out what bank isn't found, then concentrate on that?

[techy]

Thanks you all ,

i will try this trump card on my minerva ql next weekend , and let you all know the results.

can also test the memory chips to see if they are defective .

can NOT program a pal 2v2

and in ultimate swap the components with my previous 2 working trump cards