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From: harald@ccicpg.UUCP ( Harald Milne)
Newsgroups: comp.sys.amiga
Subject: Re: 68020/68881 on A2000
Message-ID: <6000@ccicpg.UUCP>
Date: Wed, 25-Nov-87 05:38:32 EST
Article-I.D.: ccicpg.6000
Posted: Wed Nov 25 05:38:32 1987
Date-Received: Sat, 28-Nov-87 15:49:31 EST
References: <1718@netsys.UUCP>
Organization: CCI CPD, Irvine CA
Lines: 54
Keywords: 68020 amiga B2000 68881 32 bit speed

In article <1718@netsys.UUCP>, bathkey@netsys.UUCP (Scott Bethke) writes:
> 	OK folks, I just got a 68020, with a 68881 (20 Mhz) for my B2000
> REV 3.9 .  Its the CSA Turbo Board, and I must say FASTMAN is VERY FAST!  But
> thats the ONLY thing that was fast.  I expected perhaps dos to speed up a bit
> maybe even dare I say math functions should go much faster even if the 
> software doesnt directly address the 68020.

	I think you mean the 68881. The 68020 is needed to interface cleanly
to the 68881. The 68020 will pass the operation to the 68881, if present.
But, and a big but at that, the 68881 will only give you a speedup if you
use 68881 instructions (an extension of 68020 instructions).

	I have asked a few questions about CSA boards a few months ago, but
got no response. I guess nobody had any. Now that I have got you on the horn
so to speak, did you perchance get a mathieedoubbas.library to replace your
stock library? Any program that uses this library (excluding amiga basic)
should notice a drastic speedup. For example Videoscape3d.

> Well since I only have the
> very first version of Sculpt 3-d and its a slow dog, I decided to run that
> to benchmark..  On a picture that normaly takes 12 hours to make with a 68000
> it took sculpt 11.5 hours with the 68020 and 20 Mhz 68881.

	I have this version also, and I am sorry to say that it does not
support 68881 instructions. The speedup you are seeing is the 68020 only.
But according to an update letter and disk I recieved for Sculpt3d, you
can get a version that does use the 68881 for $30.00. Lucky you!

> Mow I must admit
> I tried using MANX 3.4b and the +2 and +f8 options on several c programs and
> on one, I noticed instead of taking Perry's balls.c demo 80 seconds to creat
> and run the balls, it took 30 seconds..  kind-of impresive..  but I dont 
> believe this HYPE about 60 Hour Scuplts taking 45 minutes ..

	Well that does sort of sound like hype, but not by much. From what I
figure, a 25 Mhz 68881 should take a 15 hour rendering to 30 minutes.
Thats a rough guess. But it should be VERY noticeable!

> Also if only
> a handfull of Amiga applications have to address the 68020 and 68881 directly
> what good is a 68020 in my amiga?  If anyone has any Serious speed benchmarks
> and would not mind sending (email) them to me, please do so.  Id love to see    
> the difference
> 

	If there is anyway you can get a hold of Amazing Computing Volume 2,
Number 7, this should answer a lot of your questions. Lots of benchmarks.

> Scott Bethke, BATHKEY AT NETSYS.UUCP

-- 
Work: Computer Consoles Inc. (CCI), Advanced Development Group (ADG)
      Irvine, CA (RISCy business! Home of the CCI POWER 6/32)
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