Subject: Re: faster Sun3s
To: Michael Richardson <>
From: Mark Newton <>
List: m68k
Date: 09/15/1996 01:03:46
Going through old mail...

Michael Richardson wrote:

 >   I am finding my sun3/60 to be rather slow.

I saw an interesting solution to this problem on the Sun hardware FAQ
maintained by James W. Birdsall (  The FAQ
details the steps necessary to upgrade the motherboard to handle faster
CPUs.  Whether a 25MHz CPU instead of a 20MHz CPU is considered "worth it"
is left as an exercise for the reader :-)

3) Clock speed/chip upgrades to a 3/60:

        From Craig Dewick:

        The standard 3/60 has a 40Mhz master clock which is divided by
        two to get the CPU clock. One of the fortunate design quirks of
        the 3/60's for us hacker-types is that everything has its own
        oscillator. There's the master 40Mhz oscillator for the bulk of
        the major computing hardware, a 20Mhz clock for the ethernet
        hardware, another oscillator for the serial port controllers,
        and yet another one for the real time clock.

        As for interchanging chip types, 68881 and 68882 math
        coprocessors are completely interchangable. I'm running a 68020
        with a 68882 in my 3/60 and there are no compatibility problems.
        However, putting in a 68030 requires soldering in a new socket
        next to where the 68020 currently sits (since a 68030 has more

        Actually you will find that there is virtually no performance
        increase by replacing the 68020 with a 68030 because [even] if
        there is a hacked kernel that works with a 68030 on a 3/60
        board, it can't use any of the special features of the 68030
        (like the MMU cache) which the 68020 doesn't have since the 3/60
        doesn't have the required support hardware to use it (neither
        does the 3/80,  BTW).

        The only performance increase you'll get is by swapping out the
        master oscillator for faster one. My machine works fine with a
        50Mhz one, but some people have reported problems using 50Mhz
        and have had to be satisfied with 48Mhz instead.

        The only Sun-3 machines which make use of the 68030's extra
        features are the [3/4xx models], which are rackmounted,
        VME-based monsters, but good quality machines nonetheless.


        About a year ago I upgraded my 3/60 to run the CPU and math
        coprocessor at 25Mhz instead of 20MHz. It's an easy mod to do
        providing you can get a 25Mhz rated CPU and coprocessor, and you
        can find a place selling 50MHz can oscillators.

        You may need to replace the 100ns SIMMs with faster ones as
        well. I did when I upgraded my machine, but others report no
        problems with the faster clock speed.

    - mark

I tried an internal modem,      
     but it hurt when I walked.                          Mark Newton
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