SUMMARY: 2nd CPU module

From: Gary Casterline (casterln@are.Berkeley.EDU)
Date: Sat Aug 19 1995 - 04:40:40 CDT

My original question:

> I recently put a ROSS dual processor in a Sparc20.
> Do any of you see a problem with putting the old
> CPU in the 2nd slot of another Sparc20? Anything
> I should watch out for? Thanks. -Gary

Looks like I'm on safe ground if the CPUs match in clock speed
and cache type. They do so I'm going to try it.

Thanks to:

"Christopher L. Barnard" <> (Mel) (Carlos Morillo)
Scott Turvey <> (floating point solutions ltd) (Daniel Lorenzini)
Pablo Ruiz <>
Iseminger <>
Dixon Ly <>

From: "Christopher L. Barnard" <>
    I've done that on two of my SS20s without a problem. As long as the
    second processor is identical to the one that is already in there,
    you can just pop it in and turn it on.

From: Scott Turvey <>

    You may have to get a prom upgrade, depending on the speed and age =
    of the Sparc 20 receiving the 2nd CPU.

From: (floating point solutions ltd)

    The processor can go in to the second slot of the SS20, as long as it is
    the same model processor as the one in the first slot.
    If they are both model 61, you will end up with a model 612MP.
    If they are both model 50, you get a model 502MP.
    If they are both model 51, you get a model 512MP etc.
    If the SS20 is running Solaris 1, it will not work as well under MP as
    ROSS hyperSPARC. hyperSPARC with patches gives effective multiprocessing
    under SunOS 4.1.3/4.1.3_U1, whereas SuperSPARC does not.

From: (Daniel Lorenzini)

    This is definitely possible. The things to watch out for are:

    1. You should be running Solaris 2.x when you have 2 Sun
       processors. (Dual ROSS works with either SunOS 4.1.x or
       Solaris 2.x)

    2. The CPU modules must match each other exactly in a dual CPU
       configuration. This includes both clock speed (i.e., 40Mhz,
       50Mhz, etc.) and whether or not you have external cache.
       The cache is visible as a second large chip on the CPU

    3. The model 20 and 30 CPUs cannot be made into dual processor

    4. Be sure to protect yourself from flying glass. (Just
       kidding :-)

From: Pablo Ruiz <>
    We did just that couple of month ago. No problem so far...

From: Iseminger <>

    I don't know how applicable this in your case but when adding a second
    processor from Sun (a S20-71 module) to a SPARC 20 the clock speeds
    of the processors have to be the same. You can't mix a S20-61 and a
    S20-71. Also if just want to upgrade a S20-61 to a S20-71 you need a
    boot prom upgrade:

    If these modules are to replace existing 61, 51, 41, etc. modules in
    SPARC 10's or 20's, the following boot prom upgrades are required:
    #525-1383 $ 60.00/B

    #525-1377 $150.00/B

        Hope this information helps.

From: Dixon Ly <>

        If the first slot is using the same model CPU,
        it's not a problem. If it isn't, I'd be surprise
        if your system boots up.

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:10:31 CDT