ACA1233n with FPU

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Don't Panic. Please wash hands.
  • Hi all


    I wish to install an FPU on my ACA1233n but there doesn't seem to be any documentation on the process apart from to disable burst mode to improve stability.


    I have ordered a 50mhz 68882 processor. What else do I need? I'm assuming I need to buy a PGA socket and I heard I need an oscillator too.


    Also, regarding burst mode, how do you turn it off?


    Is it possible to turn the FPU on and off in software so in the times I don't need the FPU, I can have burst mode enabled for increased performance?

  • There is no official support for FPU on the ACA1233n, so pushing for an answer doesn't help - I'm answering voluntarily, without accepting a legal obligation. Operating the ACA1233n with FPU may work for some, but is not guaranteed and not recommended.


    The FPU needs a clock - this can either be given by closing the solder-jumper (this will give it the same clock as the CPU), or by installing a canned oscillator (5V type). You MUST NOT close the jumper and install an oscillator at the same time.


    Also, regarding burst mode, how do you turn it off?

    See your AmigaOS manual, "CPU" command.



    Is it possible to turn the FPU on and off in software so in the times I don't need the FPU, I can have burst mode enabled for increased performance?

    No. The mere presence of the FPU on the bus means that it adds capacitance to the address and data lines. The latter will get slower, harming signal quality from the memory chips.