> Neil Russell says on comp.os.linux:
> > * I have decided that the IDT 79R3051E (the non FPU version) should be
> > used. Since getting good pricing is hard unless quantities are high
> > I wish to stick to one type of CPU. The board will be able to
> > accommodate the IDT 79R3081E (with the FPU and more cache) if the
> > user wishes to replace the CPU. This would mean that full floating
> > point support routines need to be written; ho-hum.
> I suspect the existing FPU emulator can form the core of a IEEE
> FPU emulator. The hard part would be replacing the 387 front end
> with a mips one, assuming that the mips compiler uses a similar
> subset of IEEE FPU as the 386 one. Since they are both gcc, this
> is probably the case. Another guess: Mips FPU instructions are
> not going to be as hard to interpret as 387 ones.
FPU code is not that hard to write; I've done it before. There seems to
be a fairly large amount of people wanting the FPU though. That decision
doesn't need to be made until we do purchasing.
> > * The R3000 is able to be a little endian or a big endian machine.
> > Most operating systems that I've seen use the big endian mode, but
> > since linux runs on the 386, little endian may be more appropriate.
> I don't know if it will make that much difference, but I suppose
> little-endian is easiest. Big endian will probably make talking to
> ISA IO boards quite tricky.
I don't like the idea of hardware swapping the bits, so this favours
little endian, however, RISCos is big endian and has a few ISA bus
slots; so the software must swap the bytes itself; Mmmm, this is the
RISC way, after all...
Neil Russell (The wizard from OZ)
Pyramid Technology Email: firstname.lastname@example.org
3860 N. First Street Voice: (408) 428-7302
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