Modding a ram expansion card

[Sideburn]

Anyone know if I could simply add RAM chips to the vacant sections on this 8mb RAM expansion board to make it into a 10mb? Are those 1uf decoupling/ filter caps? would I need to add those as well?

 

[bigmessowires]

Each one of those chips is 512 KB. I'm not sure how the address decoding works, but since it seems to be designed for a 10 MB option, you could likely just add extra chips and decoupling capacitors. The caps are probably 0.1 uF, that's a common value for that purpose.

 

[Sideburn]

OK I think I have a 4MB card in a scrap PB so i was assuming I could pull the RAMS on that and put onto this card.

 

[Phipli]

OK I think I have a 4MB card in a scrap PB so i was assuming I could pull the RAMS on that and put onto this card.

Only if they're the right chips. I wouldn't assume.

Besides, better to buy some and have two cards.

 

[Sideburn]

Haha yeah of course.. Ill make sure they are the same 512k's Assuming now before I crack the thing open I mean...
Its a PB180 with 8MB is all I know at them moment...

 

[Sideburn]

Every thing worked out perfectly. I pulled 4 ram chips off my 4mb expansion card and transplanted then to the 8mb card and made it into a 10mb and it’s working flawlessly so now my PB180 is maxxed out

 

[Byrd]

Nice work, you can get a red Sharpie and tick off the 10MB option now Where did you source the small SMT caps from?

 

[Sideburn]

Nice work, you can get a red Sharpie and tick off the 10MB option now Where did you source the small SMT caps from?

Well I had some in order from eBay but the card got here first so I just lifted those off the 4mb card as well along with the RAM chips. They’re a little larger than the ones on the Kingston board but they just barely made it.

 

[bigmessowires]

Nice work! Now you could buy up all the 4MB cards on eBay and resell them as 8MB and 10MB cards.

 

[Sideburn]

Nice work! Now you could buy up all the 4MB cards on eBay and resell them as 8MB and 10MB cards.

and almost break even after adding my labor into the mix!

I actually got a pretty good deal on the 8mb. I haggled him down to $30. Another guy in France I think is making custom cards and they are really nice but $120 or so for a 10mb… a little pricey. But then the 512k chips themselves are pricey too.

 

[bigmessowires]

5 volt RAM can be pricey. If doing your own custom memory board, you could probably do it more cheaply with 3.3V RAM and some level shifters.

 

[Sideburn]

Ahh, like EPROMS too... older they are and the higher the voltage they need, the higher the price...