From: hades@coos.dartmouth.edu (Brian V. Hughes)
Subject: Re: Why does Apple give us a confusing message?
Reply-To: hades@Dartmouth.Edu
Organization: Dartmouth College, Hanover, NH
Disclaimer: Personally, I really don't care who you think I speak for.
Moderator: Rec.Arts.Comics.Info
Lines: 56

ubs@carson.u.washington.edu (University Bookstore) writes:
>bunt0003@student.tc.umn.edu (Monthian Buntan-1) writes:
>>
>>
>>Does anyone know why Apple has an ambiguous message for C650 regarding
>>fpu?  In all Mac price lists I've seen, every C650 has the message "fpu:
>>optional".  I know from what we've discussed in this newsgroup that all
>>C650 have the fpu built in except the 4/80 configuration.  Why would
>>they be so unclear about this issue in their price list?

    I think this is mostly the fault of the people who write up the
literature and price lists being confused themselves. Since there are
two possible processor configurations and one of the them doesn't have
an FPU it does seem to be an option, even though it really isn't.

>>I'm planning to buy the C650 8/230/cd pretty soon, but I'm now getting
>>confused with whether it comes with fpu or not.

    Well, then allow me to end your confusion. The C650 ONLY come with
an LC040 in the base 4/80 configuration. If you are not getting this
configuration then you are getting an FPU.

>>Why say "optional" if it's built in?

    Good question. I have been wondering that since Feb. 10th.

>If you get the Centris 650 with CD configuration, you are getting a Mac with
>a 68RC040 processor that has built-in math coprocessor support.  My 
>understanding is that the "optional fpu" refers to your option of purchasing
>the Centris 650 4/80 without FPU OR one of the other configurations WITH FPU.
 
    This is possible, but an option is something that you are supposed
to be able to request when you want it. What Apple has done is given the
buyer a CHOICE between configurations and not an OPTION.

>Apple does not offer an upgrade from the non-FPU system to become an FPU
>system.  And, it is unclear whether the '040 processor on the non-FPU system
>(a 68LC040) can be replaced with a 68RC040 supplied by another vendor.

    This is not unclear at all. In fact Apple has included in the ROMs
of those machines with LC040s code to recognize the presence of the full
040's FPU and use it. Thereby making the upgrade as easy as switching
chips. You pop the LC040 out and pop in a full '040.

>Apple did send a memo out at one point sating that the Centris 610, which ONLY
>comes with a non-FPU 68LC040 processor CANNOT be upgraded to support an FPU -
>the pin configurations of the two chips apparently do not match so you cannot
>swap one for another (again, according to Apple's memo).

    They did? I think I would double-check this. It has been stated
countless times in this newsgroup by two of the Centris hardware
designers that the LC040 and the full '040 are pin compatible and that
the C610 can be upgraded to a full '040.

-Hades

