5

I am looking for a dimensioned drawing of a 64-pin SIMM PCB like the ones used in the Macintosh II series for the ROM SIMM. I looked in Guide to the Macintosh Family Hardware and Designing Cards and Drivers for the Macintosh Family and found the pinouts but no drawings showing where to put the holes and curved features on the board. Does anyone have this?

3

Here is what you likely need. However, note that I don't own a Mac II and I therefore can't be quite definitive. But I had a thorough look at Mac ROM SIMM photographs on the internet and it seems consistent. Unless they used some specific custom-manufactured connector that looks similar to the standard without being the standard, this should be it (just double-check the dimensions with the real hardware).

The Mac ROM SIMM is much taller, though, according to what I've seen. But the height isn't a critical dimension for fitting the card in the connector, the only limit being what the case allows for.

The drawing shows the 68-pin version, but the 64-pin version has the same layout, just look at the specific values for the A, F and E dimensions that I hilighted in the table. Dimensions are given in mm[inches]

enter image description here

Source: TE/AMP 822033-2 datasheet

0

The Mac IIFX used a 64-pin SIMM for its main memory (1MB DRAM was Apple part #661-0548). 28-pin socketed ROM chips (not modules) for the Mac II (original, 1986 model) were #661-0639, -0640, -0641, -0642 if the model had the high density floppy disks, and #342-0639...if the model had the (original) double-sided floppy disks.

Other models (IIx, IIcx, IIci, IIvx, IIvi, IIsi) may have had plug-in ROM modules, but which one? Video card RAM, network card may have modules, too.

At a guess, JEDEC standard MO-116 (for 1.27mm pitch SIMM socket) drawing would apply, but Apple might have used THAT standard for the DRAM, and could have diverged for a ROM module to avoid confusion.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.