Crystal osc for Blizzard A1200/4 + 68882 FPU

[meega]

The 33MHz.

Edit: My opinion. It's right for the fpu, and gives 5 million more clocks per second for the fpu to do its stuff. (There is no requirement for a 68882 to run at cpu speed, or even an integer multiple of that speed. The more clock cycles available to it, the better.)

[meega]

Is *your* fpu a PLCC (Plastic Leaded Chip Carrier, i.e. resin square with metal prongs round the sides, sits in a socket) or a PGA (Pin Grid Array, i.e. ceramic square with pins all over the bottom, sits into a grid of holes) type of fpu?

[meega]

@rtkauer, I don't quite understand what you are saying.

@Hodgkinson, I see from this that the card does not have a CPU, only an FPU (PLCC) and some RAM, and should already have a crystal. What are you trying to do?

[meega]

rkauer wrote:
Nothing to worry about RAM expansions with coprocessors, tought.

I thought we were discussing an expansion card.

(Sorry about the typo in your name, well corrected in your quote.)

[meega]

It's designed to work with **no** additional cooling. It does not need a fan, or heatsink, or anything else. Just fit it (and the crystal) into the card, fit the card into the machine, and forget it.

I have a different A1200 expansion with such an fpu, at 33MHz, and it worked fine at rated speed. I don't think the PLCC fpu's will overclock very well, though, as I had crashes after an hour or so at 40MHz - which ceased on refitting the original crystal.

[meega]

@rkauer, Your expansion card is full! Do you happen to have any 50MHz PGA 68882's available?

[meega]

Hope it works well for you. (I'm sure that it will.) Make sure that you put them in the right way round (dots at the right end/side).

[meega]

Nothing more to do. The FPU is automatically detected and takes over all advanced maths routines, leaving the CPU free to execute program logic at the same time. Well written code will just use it!

I think that there are "stub" versions of the math libraries, but they really aren't necessary if the coder followed the rules.

Try DistantSuns Demo, you can now execute the 2.0-based version, which *requires* an FPU, whereas the 1.3 version doesn't.

Edit: available here.