How do Amiga accelerators work

vroom6sri · 05 September 2011, 12:59

This question only just occurred to me but now I just have to know... When you plop an accelerator in an Amiga (like the ACA1230 I have in my A1200) does the CPU on the card replace the work of the original CPU or do they somehow "share" the work?

DH · 05 September 2011, 13:29

Moved to an appropriate forum, as you'll get a better answer from here rather than OT

orange · 05 September 2011, 13:38

I don't think they share work. otherwise, BPPC wouldn't always have two CPUs.

iirc, someone told me once his Amiga would work with turbo card but not without it, so that it replaced broken cpu. But others say you must have working builtin CPU for initialization or something.

ajk · 06 September 2011, 11:14

As far as 68k accelerators go, they replace the original CPU. PPC cards are an exception and on those either both are active (OS3.x) or just the PPC (OS4.x) - but the motherboard CPU is still replaced in either case, it's the 68k on the accelerator doing the work.

vroom6sri · 06 September 2011, 13:41

AH! I see. I appreciate the info guys as I was curious even if I understand virtually nothing of the full technical aspects.

Actually... another question then... if the CPU on the accelerator is the new, replacement "engine" of the Amiga then is it possible for the original one to be used as some form of co-processer or dual processor?

stachu100 · 06 September 2011, 14:10

No.
020 on A1200 mobo is only used to initialize hardware during startup. After that the m68k on turbo board gets "bus granted" signal and taking over bus control keeping 020 inactive till next reset.

05 September 2011, 12:59	#1
vroom6sri Registered User Join Date: Sep 2005 Location: Peterborough Age: 47 Posts: 841	How do Amiga accelerators work This question only just occurred to me but now I just have to know... When you plop an accelerator in an Amiga (like the ACA1230 I have in my A1200) does the CPU on the card replace the work of the original CPU or do they somehow "share" the work?

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05 September 2011, 13:29	#2
DH Global Moderator Join Date: Sep 2008 Location: Might as well be WORK :( Age: 56 Posts: 4,110	Moved to an appropriate forum, as you'll get a better answer from here rather than OT

05 September 2011, 13:38	#3
orange Registered User Join Date: Apr 2007 Location: Belgrade Posts: 567	I don't think they share work. otherwise, BPPC wouldn't always have two CPUs. iirc, someone told me once his Amiga would work with turbo card but not without it, so that it replaced broken cpu. But others say you must have working builtin CPU for initialization or something.

06 September 2011, 11:14	#4
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	As far as 68k accelerators go, they replace the original CPU. PPC cards are an exception and on those either both are active (OS3.x) or just the PPC (OS4.x) - but the motherboard CPU is still replaced in either case, it's the 68k on the accelerator doing the work.

06 September 2011, 13:41	#5
vroom6sri Registered User Join Date: Sep 2005 Location: Peterborough Age: 47 Posts: 841	AH! I see. I appreciate the info guys as I was curious even if I understand virtually nothing of the full technical aspects. Actually... another question then... if the CPU on the accelerator is the new, replacement "engine" of the Amiga then is it possible for the original one to be used as some form of co-processer or dual processor?

06 September 2011, 14:10	#6
stachu100 Registered User Join Date: Mar 2009 Location: Poland Posts: 339	No. 020 on A1200 mobo is only used to initialize hardware during startup. After that the m68k on turbo board gets "bus granted" signal and taking over bus control keeping 020 inactive till next reset.

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