Apple PC Compatibility Card (7" & 12") MS-DOS 6.22 / Windows 3.11 / Windows 95B / Windows 98SE Images

stynx

New Tinkerer
Apr 7, 2025
2
1
3
Germany
I have had problems getting my 7" card to work. It turned out to be a cracked solder joint on the IBM 5x86-100 CPU. It got a hard knock or something since the pins of the QFP-CPU are stressed on the bottom, tilted on the sides and compressed on the upper side.
I reflowed all pins of the CPU and added heatsinks to all chips since they got toasty (especially the ATI Mach 64). I also had some problems with my diy Y-cable that fixed themselves after i screwed the bracket into the PCI-socket.

@croissantking : If you have a spare internal connector cable (GIMO), i would really like to test it in my 8200/120.

-Jonas
 

stynx

New Tinkerer
Apr 7, 2025
2
1
3
Germany
I have successfully changed the bus speed of the 7" Card from 33MHz to 40MHz, resulting in a 120MHz CPU speed (stable as it seems).
On the back of the card, turn the resistor R69 90 degrees to the left (connect it to 5V) onto the bottom pad of the resistor R72.

This changes the input S0 of the SC464 to high which results in the following:
Bildschirmfoto 2026-09-27 um 22.10.27.png

Not every 7"-card may take 120MHz. But i have an IBM 5x86 which are known to be have binned better than Cyrix own CPUs. AN IBM 100MHz part is basically comparable to a Cyrix 120MHz part.

Quake went up 19% from 9.8fps to 11.7 fps and the super scape benchmark goes 25% up from 50 fps to 62.5 fps which is more than expected.
There seems to be some more tweaking possible since writing is not cached at all and this reduces memory throughput to about half of what is normal.

-Jonas
 
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