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SOJ40 memory chips from VGA/Sound - what capacity exist?

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First post, by peklop

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Hi,

i know most of 2D only and early 3D PCI cards used 512kB RAM chips in SOJ 40-pin package.
Same chip was used for late Gravis Ultrasound compatible sound card.

I know newer graphic cards and AWE64 used 2MB or 4MB chips but in 42-pin SOJ package, not SOJ40.

Many 3Dfx Voodoo1 and Voodoo2 still used 40pin SOJ. 8MB cards were covered by 16 chips and 12MB cards were covered by 24 512kB chips on both sides.
But today i found some 3Ddfx Voodoo2 card are with only 12chips. It mean chips are 1MB, not 512kB.
Could be these 1MB chips used in AMD Interwave soundcards with empty socket? IMHO Interwave using 2 banks for SOJ package and bigger capacity could be used.
And in S3 Trio and Virge vga cards?

Exists 2MB or 4MB chips in SOJ-40 package? If yes, FPM or only EDO?

Second question:
Is possible make SOJ-to-SIMM adapter? Exist "fake" chip/adapter which fit into this 40pin socked?
If not, is way to drill out memory core from SOJ40 chip and solder wires to SIMM?

Reply 1 of 3, by anthony

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Memory chips with soj40 form factor exists in 256kx16 and 512kx16 variants. either Edo and fpm. These chips are very common and cheap. You can even use soj42 chips instead of soj40 with a bit of soldering

Gus pnp accept Edo as well as fpm memory. If you need more memory to Gus pnp just solder two additional simm slots or use 72 pin adapter

Reply 2 of 3, by peklop

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Thanks for reply,

i don´t want upgrade original GUS PnP and but STB SR32Pro with only SOJ Socket (not SIMM). Same SOJ socket-only are some Dynasonix and LungHwa cards.
Or this card if i buy it in future: http://www.yjfy.com/images/oldhard/sound/35-8251-01.jpg
And in first phase i don´t want solder.

file.php?id=13661
I know 512kB (256kx16) are very common and cheap.
Can be easily removed from PCI VGA cards or some are for sale here:
https://www.aliexpress.com/item/10PCS-lot-V53 … 39-bc2adf8494de

But almost all graphic cards used 512kb chips in pairs.

1MB chips used in some Voodoo2 variants are rare for me. I never had chip in my hand or card with 1MB chip plugged in socket.
512kx16 (1MB) is maximum memory variant manufactured in SOJ 40pin socket?

Reply 3 of 3, by anthony

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As I remember 512kx16 has 1 additional cas signal over 256kx16, so u must check is there this signal routed from iw chip to memory socket. If so, very much possible card will see 1mb. Iw chip has datasheet, thus you can do additional routing to memory as you wish according to memory configuration table.

512kx16 chips are common too, just send inquiry to chinese ic suppliers and they will give what you want. Price is about $1.5 in small quantities

Over 1mb 40 pin chips are not present afaik

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