​aca1221lc + A1200 FPU @ Mainboard (U0)

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Don't Panic. Please wash hands.
  • Hello,


    I'm using a socket for a FPU 68882 at A1200 mainboard (U0). Without accelerator and with FastRam ACA1211 the OS detect FPU. However if ACA1221lc accelerator is used, then the FPU is not recognized.


    Do you have any idea how to fix it, so I can use FPU @ Mainboard with ACA1221lc accelerator?


    Many thanks,

  • From my understanding, C= left the FPU off the motherboard because when an accelerator (alternate CPU) is placed in the trapdoor, the motherboard 68020 and any FPU with it are disabled. I think that will be the same in your case.

    Former GVP Tech Support 1989-93, GuruROM Maker/Supporter (as personal time allows)

  • My accelerators deliberately do not attempt to use the A1200-onboard FPU, because this requires to also route the Bus error signal from the mainboard. However, some Gayle chips cause this signal to glitch around and crash the computer randomly. So the natural fix is to avoid looking at that signal, because random crashes is not what you want on a commercial product.


    It's OK for open-source accelerators that have a number of other issues - they're slower per MHz, they do not optimize chip ram access the way we do, and it's OK for a DIY-thing to randomly crash. Not so for a commercial product :-)