[comp.sys.amiga] SetCPU/CPU Crashes My 3000

schur@venera.isi.edu (Sean Schur) (07/22/90)

I guess I am writing to Dave Haynie, but if anyone else knows great. I would
like to disable FastRam on my 3000 to see if some applications which don't 
run now might run that way. However if I use "SetCPU NOFASTRAM" in either
2.0 or 1.3 or alternately the CPU command that comes with 2.0. The system 
crashes immediately. Is there something I can do to make this work? Why would
the arguement for NoFastRam be included under 2.0 if it just crashes the 
system? Also I have tried clicking on the NoFastRam icon but it doesn't seem
to do anything. If I inquire with CPU (no arguments) after clicking it says
Fast Ram is still enabled.

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Sean Schur		       \   \  /      /
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daveh@cbmvax.commodore.com (Dave Haynie) (07/24/90)

In article <14390@venera.isi.edu> schur@venera.isi.edu (Sean Schur) writes:
>I guess I am writing to Dave Haynie, but if anyone else knows great. I would
>like to disable FastRam on my 3000 to see if some applications which don't 
>run now might run that way. 

Try the standard "SYS:System/NoFastRAM", which will turn off Fast memory.
Several of the more common programming bugs show themselves on A3000 Fast
memory, which is of course in the range $07000000-$07ffffff.  The most likely
candidates for failure are old Macintosh conversions (for example: AmigaBASIC).

>However if I use "SetCPU NOFASTRAM" in either 2.0 or 1.3 or alternately the 
>CPU command that comes with 2.0. The system crashes immediately. 

If you type "SetCPU NOFASTRAM", you are greeted with: "Error: Illegal Command
Line Option".  However, if you type "SetCPU NOFASTROM" and you're running
SetCPU V1.5, you will have your MMU shut off.  Unfortunately, the MMU is
currently required to manage the RAM-loaded OS, so you basically just yank
your OS out from under yourself.  That's not an operation you really want.
SetCPU V1.6 is clever enough to make sure it was the agent that built the MMU
setup in the first place before it will remove said setup.

>Why would the arguement for NoFastRam be included under 2.0 if it just 
>crashes the system? 

The "CPU" command would allow the creation and removal of a FASTROM image on
a ROM-based A2000.  It, like SetCPU V1.6, should verify the legality of
removing the FASTROM before it actually does the job. 

>Also I have tried clicking on the NoFastRam icon but it doesn't seem
>to do anything. If I inquire with CPU (no arguments) after clicking it says
>Fast Ram is still enabled.

You're obviously confusing ROM with RAM.  Disabling Fast RAM is what you're
after for testing of old, buggy software.  The SetCPU or CPU tools have 
absolutely nothing to do with this.  They're reporting on the existence of
a RAM-based ROM image, otherwise known as a FASTROM (because that's what I
called it originally, not real scientific explanation here).  In some cases,
a FASTROM image is reversable, in other cases, it isn't.  SetCPU always knew
the difference if it had set up the ROM image, but V1.5 didn't take into
account that other programs might play MMU games before it got called up.
V1.6 fixes that.


>Sean Schur		       \   \  /      /

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