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Operating System Specific Discussions => Amiga OS => Amiga OS -- Development => Topic started by: DamageX on April 24, 2006, 08:37:29 AM

Title: more 68K questions
Post by: DamageX on April 24, 2006, 08:37:29 AM

Somehow I've written something that runs with the '030 but crashes on the 68000. I tried adding an MC68000 directive for phxass but that didn't help. Anyone know a good doc that lists the instructions existing on '020+ that aren't on the 68000?

Also, with mediocre speakers and the noise from fans and harddrive motors, how am I supposed to tell if my 14-bit Paula audio player is working correctly (and better than 8-bit) ?

Title: Re: more 68K questions
Post by: Piru on April 24, 2006, 09:44:09 AM

http://www.freescale.com/files/archives/doc/ref_manual/M68000PRM.pdf

In addition there are some other limitations to 68000 barring the instruction set:

- The easiest way to crash 68000 is to access word or longword data from odd address.

example:

Code: [Select]


  lea    data(pc),a0
  move.w 1(a0),d0
  rts

  even
data:
  dc.b   1,2,3

- Another easy way to mess up is to use *2, *4, or *8 index on instructions (multiplier is simply ignored by 68000).

example:

Code: [Select]


  move.l 0(a0,d0.w*2),d0
  rts


Title: Re: more 68K questions
Post by: bloodline on April 24, 2006, 11:25:34 AM

Quote

DamageX wrote:

Also, with mediocre speakers and the noise from fans and harddrive motors, how am I supposed to tell if my 14-bit Paula audio player is working correctly (and better than 8-bit) ?

If you have to ask that question... I don't think you need 14bit :-)

Title: Re: more 68K questions
Post by: darksun9210 on April 24, 2006, 01:48:15 PM

Quote

DamageX wrote: Also, with mediocre speakers and the noise from fans and harddrive motors, how am I supposed to tell if my 14-bit Paula audio player is working correctly (and better than 8-bit) ?

hmmm, crank it right up? :-D

or do you mean you are getting a humming noise from the speakers? - if so, move the power for the speakers/amp to a sperate wall socket outlet. this should clear up any gound loop issues. or maybe a shielded power strip?

Title: Re: more 68K questions
Post by: DamageX on April 24, 2006, 07:21:31 PM

Quote

The easiest way to crash 68000 is to access word or longword data from odd address.

Oh yeah, I'm guilty of that (^_^')

Quote

If you have to ask that question... I don't think you need 14bit

That's probably true... even 8-bit sounds pretty good with the low-pass filter turned off. But I want the bragging rights for 14-bit anyway... Maybe I'll borrow some better speakers from my brother.

Title: Re: more 68K questions
Post by: Jose on April 24, 2006, 08:25:20 PM

@DamageX

Don't forget to calibrate it. To me it made a big difference (still not like a decent sound card of course).