68kMLA Classic Interface
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| Modding a ram expansion card | |
| Posted by: Sideburn on 2023-10-18 11:31:35 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?   | |
| Posted by: bigmessowires on 2023-10-18 11:40:08 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. | |
| Posted by: Sideburn on 2023-10-18 11:51:27 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. | |
Posted by: Phipli on 2023-10-18 11:56:03OK 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. | |
| Posted by: Sideburn on 2023-10-18 12:02:07 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... | |
| Posted by: Sideburn on 2023-10-21 02:12:15 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 🙂   | |
| Posted by: Byrd on 2023-10-21 03:03:36 Nice work, you can get a red Sharpie and tick off the 10MB option now 🙂 Where did you source the small SMT caps from? | |
Posted by: Sideburn on 2023-10-21 07:27:57Nice 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. | |
| Posted by: bigmessowires on 2023-10-21 07:38:45 Nice work! Now you could buy up all the 4MB cards on eBay and resell them as 8MB and 10MB cards. 😉 | |
Posted by: Sideburn on 2023-10-21 07:49:48Nice 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. | |
| Posted by: bigmessowires on 2023-10-21 08:19:44 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. | |
| Posted by: Sideburn on 2023-10-21 08:22:10 Ahh, like EPROMS too... older they are and the higher the voltage they need, the higher the price... | |
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