From: mpretzel@cs.utexas.edu (Benjamin W. Allums)
Subject: Re: Mac II SCSI & PMMU socket question
Organization: CS Dept, University of Texas at Austin
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Distribution: world
NNTP-Posting-Host: tokio.cs.utexas.edu

In article <1qkmb2$n0d@jethro.Corp.Sun.COM> khc@marantz.Corp.Sun.COM writes:

>1. The Mac II is supposed to have a socket for the MC68851 PMMU chip. Could
>anyone let me know where that socket is on the motherboard. I have obtained
>a PMMU chip (16 Mhz) from a surplus store, and would like to install it onto
>my Mac II (circa 1987). But I cannot see the socket myself when I tried to
>install it.

The original Mac II had an Apple MMU chip installed which performs a subset
of the 68851's functions.  If you look underneath your front left floppy
bay you will find three chips, all approximately the same size.  One will
be the 68020, the next the 68881, and the third, approximately the same
size, will be the Apple chip.  It is easy to spot because it has a 'hump'
in the middle of it.


Example:


                         -----------
                        /           \
         ---------------             ---------------
         |                                         |
         |                                         |

That and the Apple logo should make it easy to find.

Ben
mpretzel@cs.utexas.edu
