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Digital 54-22703-01 Motherboard – L2 Cache

After making this motherboard fit into the IBM PS55/z, I realised I hadn't decked it out fully. I'd mentioned cache in the first post, and finally got around to ordering some. The goal was to speed up the poor old 486 as it wasn't running as fast as I would've expected it to. Of course, this was also all very subjected as it'd be pretty impossible to actually remember how fast my first PC actually ran!

Usually, parts like this can be pilfered from other items laying on the shelves in my apartment, but this motherboard needed specific 'TAG' RAM, as well as the standard 32KBx8 static RAM chips. I had to go hunting...

Required components

Back to Pafe 45 of the User Manual for this motherboard and we find that we need eight 32 KB x 8 cache SRAM chips and three 16 KB x 4 cache tag SRAM chips to max it out. Straight to eBay and I found a seller in Israel with the correct parts. I incorrectly ordered two sets of TAG RAM chips and only half the required static RAM chips... whoops... fortunately I could pilfer those off another board!


The TAG RAM chips are labelled MCM6290BP25 RIQAB9131.


As per usual... always be careful when inserting ICs. Make sure their legs are aligned with the sockets and don't press until it's safe... otherwise this happens!



With everything in, we just need to adjust the jumpers...


Set all four jumpers (J3,J4,J6,J7) to 2-3... and then boot!



Test Software

Go here and download anything that starts with Cache. I then tested them all out...

DSC05527 DSC05528 DSC05531

They all showed that any data size under 256kb proved quick response times. The rest started spiking as more operations were required. The CCT386 application had awesome graphs.


Now to work out if the games actually operate faster...

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