Unknown memory expansion card

[roelofw]

Any information on this card?

 

[Robin4]

dont know the brand.

But it seems to me that it is a 512KB memory card.. With such low capacity i almost sure, its some kind of `back fill card` specially for the IBM XT computer with you have the older gen 64K -256KB motherboard.. So you could back fill it to 640KB of conventional memory.
I also have seen that card on marktplaats. But skipped it, because i dont have a XT class IBM with a lower capacity memory on the motherboard.

 

[twolazy]

Is there an FCC ID anywhere on the card? Don't see one on the front...

 

[Robin4]

iam doing a wild guess..

Maybe a captain board? Those where regulary used in XT class machines.


edit:

Have checked it, but no tecmar captain card.

 

[modem7]

But it seems to me that it is a 512KB memory card..

There is no need to speculate about that. The card has '512K RAM CARD' printed on it.

This is a simple RAM card. The switches will be to control the starting address of the RAM, and to control the count of enabled banks. And one switch may be to enable/disable RAM parity checking by the card.

Speculation:
Maybe, three of the four switches in the blue switch block control the count of enabled banks. (2 to the power of 3 = 8 banks, at most)
Maybe, one of the four switches in the blue switch block enables/disables RAM parity checking by the card.
Maybe, the black switch block controls the starting address of the RAM.

Hopefully, documentation will be found.

 

[roelofw]

Got the card working in one of my 5155's!
My 'original' sixpack expansion card didn't work. I replaced the chips from the sixpack.

Now 640kb again.
No further documentation found, but no further need for it

 

[Robin4]

That color of the pcb with that color of the components i would think it could be a NEL electronics card. or Something like JUKO ST.