narcotic wrote on 2022-03-26, 19:56:

Hi, where can I get cache modules PC 330-486, PC 350-486 board. It has to connect 8 memory banks up to 256kb.
Here are the specifications of my board: https://stason.org/TULARC/pc/motherboards/I/I … PC-350-486.html

That board requires nine standard fast CMOS SRAM chips, the 32K * 8 type in the narrow (aka skinny, 300 mil) 28-pin DIP package. The board uses 5V signalling, so you don't want low-voltage chips (avoid "V" in he model numer) Probably 20ns would work at default settings, but getting 15ns modules leaves more room for higher bus clocks (like 40MHz) or aggressive cache timings. As 32K addresses of 8 bits each make up 256 kilobits (or 256 kibibits if we use the proposed SI nomenclature), the model numbers of those chips often include "256". I searched ebay for "32K x 8 static ram DIP 28" and found some offers for the correct type of chip, e.g. W24257AK-15 or IS61M256-15N.

mkarcher wrote on 2022-03-26, 20:45:

narcotic wrote on 2022-03-26, 19:56:

Hi, where can I get cache modules PC 330-486, PC 350-486 board. It has to connect 8 memory banks up to 256kb.
Here are the specifications of my board: https://stason.org/TULARC/pc/motherboards/I/I … PC-350-486.html

That board requires nine standard fast CMOS SRAM chips, the 32K * 8 type in the narrow (aka skinny, 300 mil) 28-pin DIP package. The board uses 5V signalling, so you don't want low-voltage chips (avoid "V" in he model numer) Probably 20ns would work at default settings, but getting 15ns modules leaves more room for higher bus clocks (like 40MHz) or aggressive cache timings. As 32K addresses of 8 bits each make up 256 kilobits (or 256 kibibits if we use the proposed SI nomenclature), the model numbers of those chips often include "256". I searched ebay for "32K x 8 static ram DIP 28" and found some offers for the correct type of chip, e.g. W24257AK-15 or IS61M256-15N.

Thank you very much for your answer, it could be worth these that I have found:
https://es.aliexpress.com/item/4000490415083. … arch-mainSearch

Those don't even have a brand on them. Who knows what they originally were sold as.

cyclone3d wrote on 2022-03-27, 00:14:

Those don't even have a brand on them. Who knows what they originally were sold as.

🤣 fake chips ? ;p

narcotic wrote on 2022-03-26, 21:17:

Thank you very much for your answer, it could be worth these that I have found:
https://es.aliexpress.com/item/4000490415083. … arch-mainSearch

Those chips have the right model number printed on them, but that printing defenitely is not the one used by Winbond when they "invented" that number. So, these chips are no-brand suppsed clones. They might be factry rejects, relabeled 20ns RAM, empty cases or just fine 15ns SRAM. It's a pity that you don't get any reliable indicator of the quality of the compnents in this kind of offer. If you are willing to risk the money an deal with troubleshtinig if the chips don't work out, you can gamble on them and buy two packs of 5. The chance that 9 out of ten work, at least at 20ns access time, is not that bad, actually.

mkarcher wrote on 2022-03-27, 10:55:

narcotic wrote on 2022-03-26, 21:17:

Thank you very much for your answer, it could be worth these that I have found:
https://es.aliexpress.com/item/4000490415083. … arch-mainSearch

Those chips have the right model number printed on them, but that printing defenitely is not the one used by Winbond when they "invented" that number. So, these chips are no-brand suppsed clones. They might be factry rejects, relabeled 20ns RAM, empty cases or just fine 15ns SRAM. It's a pity that you don't get any reliable indicator of the quality of the compnents in this kind of offer. If you are willing to risk the money an deal with troubleshtinig if the chips don't work out, you can gamble on them and buy two packs of 5. The chance that 9 out of ten work, at least at 20ns access time, is not that bad, actually.

Yes, I understand they are fake, I'll take my chances knowing the correct model is good enough for me. If I see that the Chinese have cheated me I will open a dispute and get my money back. I will tell you how it went.

Hi, I have already got the 9 memory modules. But I find a problem, in the top row of memory banks that are 5 if they are the size of the modules, but in the bottom row are 4 and have 2 extra pins. I also don't know in which direction the modules have to be connected.

Place it so the 4 missing pins are on the "notch" side.
The opposite of what the last pic shows.
Should work just fine then!

bofh.fromhell wrote on 2022-04-25, 18:05:

Place it so the 4 missing pins are on the "notch" side.
The opposite of what the last pic shows.
Should work just fine then!

Then I connect it like in the picture below?
or the notch starting from the bottom?
at the base has the notch at the top.

I managed to install the 256kb cache memory 😀