From: sgberg@charon.bloomington.in.us (Stefan G. Berg)
Subject: Re: Motorola XC68882RC33 and RC50
Reply-To: sgberg@charon.bloomington.in.us (Stefan Berg)
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In article <16APR199323531467@rosie.uh.edu> st1my@rosie.uh.edu (Stich, Christian E.) writes:
> I just installed a Motorola XC68882RC50 FPU in an Amiga A2630 board (25 MHz
> 68030 + 68882 with capability to clock the FPU separately).  Previously
> a MC68882RC25 was installed and everything was working perfectly.  Now the
> systems displays a yellow screen (indicating a exception) when it check for
> the presence/type of FPU.  When I reinstall an MC68882RC25 the system works
> fine, but with the XC68882 even at 25 MHz it does not work.  The designer
> of the board mentioned that putting a pullup resistor on data_strobe (470 Ohm)
> might help, but that didn't change anything.  Does anybody have some
> suggestions what I could do?  Does this look like a CPU-FPU communications
> problem or is the particular chip dead (it is a pull, not new)?
> Moreover, the place I bought it from is sending me an XC68882RC33.  I thought
> that the 68882RC33 were labeled MC not XC (for not finalized mask design). 
> Are there any MC68882RC33?

I, too, have a XC68882RC50 math coprocessor, which I installed
succesfully in my Mega Midget Racer (clocked at 33 MHz). I have tried
clocking my FPU at 28 to 50 MHz and it all worked just fine. I have a
MC68030-33 CPU. I don't know why my FPU has an XC (my original 33MHz FPU
was label MC68882-33), but it seems to work fine on my system. Maybe you
just have a bad chip.

Stefan

P.S. Or does it mean eXperimental Chip instead of Motorola Chip? .-)
