Re: [cobalt-developers] Re: Cobalt MIPS CPU

[Chris Johnson <cjohnson@xxxxxxxxxxxxx>]

	> Date   : Fri, 02 Jun 2000 10:09:25 +0200
	> From   : Andrew Tuckey <tuckey@xxxxxxxxxxxx>
	> 
	> Subject: [cobalt-developers] Re: Cobalt MIPS CPU
	> 
	> I have some questions about the 64-bit 'ness of the MIPS
	> processors used in the Qube and RaQ(2).

    The Qube-1 2700 used a 150 MHz QED RM5230, as does
    the Raq-1. The 175 MHz RM5320 is a later spin of the
    same chip, but I don't believe that we ever used this
    speed.  These product lines were replaced by the
    Qube-2 and Raq-2 long ago. (How long is 14 months in
    internet time?)

    The Qube-2 uses 250 Mhz QED RM RM5231.

    These Cobalt product lines are 64-bit in the same
    manner that Sun's UltraSparc line was 64-bit in the
    Solaris 2.6 and 2.5 days.  The OS does not provide
    any particular 64-bit features, but the on-chip
    interfaces are 64-bits wide.  There is a benefit to
    this, with cache references, for example, but that
    is about it.

    Mashey has some great postings in comp.arch when Mips
    rolled out the R4000 about what '64-bits' means.  Our
    PR literature is following silicon valley marketing
    traditions.

    Another point is that if we described these systems
    as 32-bit Mips platforms, people would assume that
    we were using 8 year old technology.  Then this note
    would be explaining that our systems actually do
    support the Mips III and IV instructions set extensions.

    Chris