[Solved] Cyrix 100QP SQFP packaging orientation (It have two arrows) \ VOGONS

[Solved] Cyrix 100QP SQFP packaging orientation (It have two arrows)

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First post, by Rav

Posted on 2023-06-20, 23:48

Rav Offline

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Hi there, I just received a "new" cpu and I got a weird issue.
Usually I have no issue orienting the CPU for the socket but that one have two arrow. And the only reference I got for a picture is that one : https://www.x86-guide.net/en/cpu/Cyrix-5x86-1 … cpu-no2275.html

From that picture, it look like it's upside down.
Can someone can confirm what arrow is the correct one and if I will let the magic smoke go out if I socket it like in the image showed in the previous link

Here the picture of that new CPU, on the side of the older CPU.

The attachment cpu.jpeg is no longer available

Last edited by Rav on 2023-06-21, 05:21. Edited 1 time in total.

Reply 1 of 4, by Anonymous Coward

Posted on 2023-06-21, 00:43

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In theory, the correct triangle to align with is the larger one on the outer edge of the PCB.
However, when you're dealing with jerry rigged cheapskate parts made with scab labour, who really knows.
To be safe you could consult the 5x86 pdf manual and use a multimeter to see which pins go where.

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V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 2 of 4, by BitWrangler

Posted on 2023-06-21, 00:57

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Anonymous Coward wrote on 2023-06-21, 00:43:

In theory, the correct triangle to align with is the larger one on the outer edge of the PCB.

Seconded.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 3 of 4, by Rav

Posted on 2023-06-21, 02:32

Rav Offline

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Found the correct orientation.

By putting the CPU in the light, I could see the ground trace and properly identified E1,G1,H1,K1,L1,M1 VSS.
The Image from the side is upside down, the big arrow is right.

Reply 4 of 4, by Rav

Posted on 2023-06-21, 05:25

Rav Offline

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That's a nice 486 so far, 11.9FPS on dosbench option C (Quake timedemo)

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