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From: hades@coos.dartmouth.edu (Brian V. Hughes)
Subject: Re: Centris 650 Math CoProcessor option
Message-ID: <C5qKq0.9oK@dartvax.dartmouth.edu>
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Reply-To: hades@Dartmouth.Edu
Organization: Dartmouth College, Hanover, NH
Disclaimer: Personally, I really don't care who you think I speak for.
References: <79731@cup.portal.com>
Distribution: usa
Date: Mon, 19 Apr 1993 15:08:23 GMT
Moderator: Rec.Arts.Comics.Info
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David_Anthony_Guevara@cup.portal.com writes:

>Sorry if this is a FAQ.  I don't normally read comp.sys.mac.hardware.
>I am purchasing a couple of Centris 650's.  I configured the systems
>as follows:

>	Eight (8) Mb RAM
>	Ethernet
>	1 Mb VRAM
>	Math CoProcessor option

>My purchasing agent told me about the math coprocessor option and sent
>me the Apple summary documentation to prove it.  I ordered the coprocessor
>option, but I'm really not sure that we needed it.  I thought the '040 chip
>had a math coprocessor built into it.  Has Apple had a math coprocessor chip
>architectured to keep up with the speed of the '040 chip in the Centris 650?
>I am concerned that I may have set up a hardware bottleneck.

    Apple has really confused people with this whole thing. I think
we'll be answering this question for about the next year or so. There is
no "option" to get an FPU on a C650. What you have is a choice of CPUs:
there is the 68LC040 that does not have an integrated FPU like the full
'040 and is only present in the base 4/80 model of the C650 (AppleUSA).
And there is the full '040 which you get when you order anything other
than the base 4/80 configuration. Therefore, since you have ordered one
of the 8MB versions with on-board Ethernet models you will not be
getting the LC040. But even if you wanted to have the LC040 you wouldn't
be able to order a C650 with 8MB RAM, on-board Ethernet and an LC040.
It's not an "option."
    Also, a note to people out there that have 4/80 C650s and C610s
thinking that there is an optional FPU, the '040 class chip cannot
recognize an external FPU, so there is no socket on the motherboard for
a FPU chip and you cannot go out and purchase an FPU on a PDS card or
something like that. The only way to get an FPU in these machines is to
replace the LC040 with a full '040. And if you have a C610, you will not
need to worry about a heat sink if you do replace the LC040 with the
full '040, but if you have a 4/80 C650 you do need to have a heat sink.

-Hades

