SUMMARY: what is 60MHz module / 50Mhz MXCC equal??

From: John Dyson (
Date: Fri Jun 23 1995 - 23:26:12 CDT

Thanks alot for the help - I got three quick responses that said about the =
thine and gave me the info that I needed and learned a few things in the =
process. =20

Thanks to:

=46rom Guy Harris:

> I am running a SPARC 20 right now and have added
>an new SPARC module (501-2519). The FEH1 says this
>is a 60MHz module, but the MXCC runs only at 50MHz (what
>is a MXCC??).

I think it stands for "Mbus/XDbus Cache Controller".

SuperSPARC is a one-chip microprocessor that includes:

        1) integer, floating-point, and memory-management units;

        2) a 20K-byte on-chip instruction cache and a 16K-byte on-chip
           data cache;

        3) an interface to Sun's Mbus, as used on the SPARCstation 10
           and 20, clones of those machines (and some non-clone machines
           such as Auspex machines), and the older SPARCserver 600MP;

        4) an interface to an MXCC.

An MXCC, also known as "SuperCache", is a chip that connects to a
SuperSPARC chip (the two chips are normally mounted on a single
daughterboard, i.e. an Mbus or XDbus module, along with the cache RAM
that the MXCC controls) and includes:

        1) a cache controller for a 1 megabyte or 2 megabyte unified
           instruction-and-data cache;

        2) an interface to Sun's Mbus;

        3) an interface to Sun's XDbus, used on the SPARCserver 1000,
           SPARCcenter 2000, and some large Cray machine that is

I think the Mbus in a SPARCstation 20 runs at 50 MHz (and that the one
in current SS10's runs at 40 MHz). I also think this means that if you
have a 60 MHz SuperSPARC processor, it *cannot* directly plug into the
Mbus on an SS20, because the chip doesn't run at the same speed as the

However, an MXCC *can* plug into both a 60 MHz SuperSPARC and a 50 MHz
Mbus at the same time - in fact, that's what you have, I suspect, and
that's probably why the FEH1 (Field Engineer's Handbook?) says that the
MXCC is running at 50 MHz.

>My question is, is this a SPARC 20/50,
>a SPARC 20/51, or even a SPARC 20/6x????

I suspect Sun calls it a SPARCstation 20 model 6x; a page on Sun's Web
site indicates that, for example, an SS20 with one 60 MHz SuperSPARC
processor is a "Model 61".

Also, some other info from Casper Dik --

You can check with prtconf which speed the machine is running.

Somewhere in prtconf -vp you'll find:

    Node 0xffd490e0
        clock-frequency: 03938700 <<<---- 60MHz (hex)
        name: 'TI,TMS390Z55' <<<- SuperSPARC processor.
        ecache-parity?: =20
        bfill?: =20
        bcopy?: =20
   [rest deleted]


This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:10:27 CDT