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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: beltrixx on January 06, 2008, 07:00:20 PM

Title: Which co-processor speed for my Microbotics 1230@50??
Post by: beltrixx on January 06, 2008, 07:00:20 PM

Hi,

I've just acquired a XC68882A40 copro for my Microbotics XA1230 accelerator card, but I've just realized that the copro speed is 40 MHz whilst the 68030 processor speed is 50 MHz ...

Do you think this can be a problem? Am I overclocking the copro or it uses a separate clock ?

Thanks in advance.

Title: Re: Which co-processor speed for my Microbotics 1230@50??
Post by: bloodline on January 06, 2008, 07:26:39 PM

No, it should be fine. The FPU is almost never used on the Amiga anyway.

Title: Re: Which co-processor speed for my Microbotics 1230@50??
Post by: Damion on January 06, 2008, 09:17:59 PM

From what I can see looking at BBOAH, it requires a separate oscillator for the FPU, in which case you can run it at 40Mhz. (50 would likely be OK though.)
 

Title: Re: Which co-processor speed for my Microbotics 1230@50??
Post by: beltrixx on January 06, 2008, 09:29:44 PM

Thanks for yor replies.

I understand that no sepparate clock is needed, isn't it?

Greetings,

Manel.

Title: Re: Which co-processor speed for my Microbotics 1230@50??
Post by: Hodgkinson on January 06, 2008, 09:43:32 PM

Hmmm. I believe FPU's are normally intended to run at a higher frequency than the CPU - Eg, normal A1200 has a 68882 on a A1200/4 clocked at around 33Mhz. On most 68030@50Mhz boards the FPU's are also ran at 50Mhz.
EDIT: Im sure I saw that in a 68882 datasheet somewhere...Might be wrong though...

That empty socket will need a crystal for the FPU...Whatever frequency the FPU is...

Putting a incorrect FPU (That is, forcing it to run at a higher frequency) into a card, even if the FPU is rarely used by the system, could result in a toasted FPU and/or other components.
Mismatched clock frequencies also have a tendeny of resulting in data communication errors between IC's.

To be safe Id recommend that you try to get a 50Mhz FPU (And associated crystal) for your card...And make sure that its the correct pin configuration (PLCC or PGA).

Hodgkinson.