3 ms·

Not sure about the rest, but I thought it was funny that the 80286 CPU is among the smallest chips on the board - that's probably due to the PLCC (?) packaging,

by rob74 2y ago

Not sure about the rest, but I thought it was funny that the 80286 CPU is among the smallest chips on the board - that's probably due to the PLCC (?) packaging, while most of the others are DIP, but still... The only other PLCC-packaged chips are two ATF1508AS, which are indeed ASICs (CPLDs) - oh, and the 53C400, which is... a SCSI controller (probably added as a bonus?!).

shiroiushi 2y ago
>I thought it was funny that the 80286 CPU is among the smallest chips on the board - that's probably due to the PLCC (?) packaging, while most of the others are DIP That's basically it. The 286 has a much larger wafer inside than a typical DIP, and DIPs are extremely inefficient packages. It would be interesting to see how much you could shrink this board down if all these chips were replaced with BGAs (using the same wafers inside). Obviously, that's not really feasible (no one is selling a BGA version of an 8259 interrupt controller, much less an 80286), but it would be interesting to see the dramatic size reduction, just from packaging waste. Also interesting would be if you designed a board using BGA versions of all these chips, but fabbed on modern IC processes (thus yielding much smaller wafers. and therefore somewhat smaller BGA packages). Of course, the whole thing could probably just be implemented with a single FPGA these days.
- rob74 2y ago
  TBH that's nothing new... for instance, it takes a while to find the 68020 CPU on the Amiga 1200 mainboard: https://bigbookofamigahardware.com/bboah/media/download_photos/a1200mb_rev1d4.jpg https://bigbookofamigahardware.com/bboah/media/download_phot...
stephen_g 2y ago
Just a note, CPLDs (and the more modern replacements, FPGAs) are kind of the opposite of ASICs by definition. They are obviously ICs, but being programmable they’re general purpose, not application specific (the AS in ASIC).

by rob74 2y ago

shiroiushi 2y ago

>I thought it was funny that the 80286 CPU is among the smallest chips on the board - that's probably due to the PLCC (?) packaging, while most of the others are DIP That's basically it. The 286 has a much larger wafer inside than a typical DIP, and DIPs are extremely inefficient packages. It would be interesting to see how much you could shrink this board down if all these chips were replaced with BGAs (using the same wafers inside). Obviously, that's not really feasible (no one is selling a BGA version of an 8259 interrupt controller, much less an 80286), but it would be interesting to see the dramatic size reduction, just from packaging waste. Also interesting would be if you designed a board using BGA versions of all these chips, but fabbed on modern IC processes (thus yielding much smaller wafers. and therefore somewhat smaller BGA packages). Of course, the whole thing could probably just be implemented with a single FPGA these days.

rob74 2y ago
TBH that's nothing new... for instance, it takes a while to find the 68020 CPU on the Amiga 1200 mainboard: https://bigbookofamigahardware.com/bboah/media/download_photos/a1200mb_rev1d4.jpg https://bigbookofamigahardware.com/bboah/media/download_phot...

stephen_g 2y ago

Just a note, CPLDs (and the more modern replacements, FPGAs) are kind of the opposite of ASICs by definition. They are obviously ICs, but being programmable they’re general purpose, not application specific (the AS in ASIC).