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Old 20 January 2008, 20:52   #1
DoogUK
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A1200 with onboard 6881, anyone done it?

according to schematics..the u0 site is for a 68881 fpu...has anyone eer seen one in place?
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Old 20 January 2008, 21:03   #2
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Is this the spot on the orig. mobo? (Not too far from the trapdoor/along the front edge I've never looked at the schematic )
I wondered what that was for... I thought it was for some kind of CPU/FPU.
Wonder what would happen if you put one on?
Surely there would be more to it than just soldering one in though (signals, timing, memory stuff etc.) thats assuming that the circuit tracks or whatever are complete and working.

We need Zetr0 or something...
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Old 20 January 2008, 21:05   #3
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thats the one....right next to the cpu, i was just looking at the revision 2 schematics...and its listed as the mc68881
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Old 20 January 2008, 21:12   #4
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Well some Googling revealed crappy, poorly put together docs from the early 90s (as usual) with info about the A1200 and that FPU is listed as optional, weather that is pre release stuff, false, or the remains of a abandoned Commodore cost cutting measure, I guess we will never know.

Mind you one of my A1200s box/manual also claims the system has 1Mb with a option to upgrade to 2Mb so who knows

I would have gone with the theory Commodore left it out (costs), I don't remember much using the things being out around the time anyhow, and if you wanted to do ray tracing, CGI etc. you would proberly have baught either a big box Amiga with some kind of accelerator or a accelerator anyhow.
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Old 20 January 2008, 21:13   #5
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you would need a smidge of circuitry not only for timing but also for allowing the fpu to take over selected operations, (both in and out) from the CPU
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Old 20 January 2008, 21:23   #6
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This doc is from 92 from Commodore :

http://www.ianstedman.co.uk/Downloads/A1200FuncSpec.txt

It mentions the FPU as optional.
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Old 20 January 2008, 22:05   #7
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The schematics probably have the missing components close by. Try it and see? Then again, it's not much use and will not really speed up the A1200.. :-)
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Old 20 January 2008, 23:00   #8
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i only realy understand the basics of schematics, so wouldnt know.....i have the whole lot if anyone wants them to take a look
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