Name:         Macintosh System 7.5.5 Update
Version:      n/a
Released:     September 18, 1996
A set of system software enhancements that improves the
reliability and performance of all Macintosh and Mac
OS-compatible computers running system software version
7.5.3. Also includes all of the improvements delivered with
System 7.5.3 Revision 2. For complete information, please
see the Read Me included with this software.

Path to this software:
  Apple SW Updates
          System 7.5.5 Update
            Sys 7.5.5 Update
            Sys 7.5.5 Update-1of3.sea
            Sys 7.5.5 Update-2of3.sea
            Sys 7.5.5 Update-3of3.sea
            Sys 7.5.5 Update-NetInstall.sea
            Sys 7.5.5 Update-Q and A

This software is available in two formats (disk images and
"Net Install"):

1.  Three self-extracting archives of Disk Copy 1440K disk
images.  To use, download, double-click the downloaded file
(this decompresses it), and use Disk Copy to create the
disks.  Disk Copy can be found in the Utilities folder
posted here.

2.  A complete System 7.5.5 Update "Net Install".  It
includes all software from all three System 7.5.5 Update
disk images.  This posting is provided as a convenience for
those customers who:
- want to download just one file.
- want a pre-configured "Net Install" to place on their
hard drive or on a server.

Name as Posted              Actual Disk Name
Sys 7.5.5 Update-1of3.sea   System 7.5.5 Update - 1
Sys 7.5.5 Update-2of3.sea   System 7.5.5 Update - 2
Sys 7.5.5 Update-3of3.sea   System 7.5.5 Update - 3

You do not need to download the "Net Install" if you have
already downloaded the three separate disk images of System
7.5.5 Update.

Macintosh System 7.5.5 Update Overview

Who should install the System 7.5.5 Update?

Apple recommends that all customers who are currently using
System 7.5.3 should install the System 7.5.5 Update.  If
you are using a system software version prior to System
7.5.3, you must upgrade to System 7.5.3 before you install
this update.  (If you are using System 7.5, 7.5.1, or
7.5.2, you can use System 7.5 Update 2.0 to upgrade to
System 7.5.3.).

What does installing the System 7.5.5 Update do?

After you install the System 7.5.5 Update, you should
notice improved performance and stability, specifically:

-  Significant performance improvements when using virtual
memory. If you use virtual memory, this software improves the
time it takes to:
   -  launch a large application program that requires a
      significant amount of RAM
   -  switch between large application programs
   -  switch between large documents within an application
   -  access SCSI devices

-  Improved memory management on PowerPC computers
If you could not launch an application program because you
did not have enough RAM to open it, you may be able to use
the application after you install this update.   
This update also eliminates the cause of one Type 11 error.

-  Improved reliability when using floppy disks in a
computer equipped with a DOS Compatibility Card
If you have a computer with a DOS compatibility card
installed, you may have experienced problems inserting
floppy disks while Windows is launching.  This software
fixes this problem.

-  Improved reliability on PowerPC PowerBook computers
(PowerBook 5300 and  2300 series computers) and PCI-based
computers (Macintosh 5400, 6400, 7200, 7500, 7600, 8500,
and 9500 series computers)
If you have a PowerPC PowerBook or a PCI-based computer,
your computer may have "frozen" from time to time while
accessing a hard disk.  This update fixes one cause of this

-  Improved reliability when using Ethernet and virtual
If you use Ethernet and have virtual memory turned on, you
may have experienced problems transferring large files over
Ethernet.  This update fixes this problem.

-  Better reliability when using the Apple TV Tuner or
Macintosh TV Remote Control
When using the remote control for the Apple Video Player,
the channel and volume buttons may have stopped working
when you press them rapidly.  This software fixes this

-  Improvements in LocalTalk
This update includes improvements in LocalTalk that
   -  better reliability on Macintosh 5400 series computers
   -  better performance when using some third-party
      infrared software products

-  Improved stability when using multiple background
application programs
If your computer crashed when using more than one
background program, this update fixes the problem.  A
background program is one that works behind the scenes, so
you don't see it in the Application menu.  Some e-mail
programs have this background feature.

-  Improved stability when using a shared printer on a
If your computer crashed when you were trying to use a
shared printer on a network, this update fixes the problem.

- Improved reliability on high performance (180MHz or
greater) Macintosh and Mac OS-compatible computers that
have the PowerPC 604 or 604e processors
If you have experienced system freezes during startup or
difficulties when formatting floppy disks, this update
fixes these problems.

- Improved reliability when using Ethernet on the Macintosh
5400 and 6400 series computers

- Improved reliability when using sound intensive
applications on  Macintosh Quadra and Centris computers
that contain the PowerPC upgrade card

- The "System 7.5.5" extension set in Extensions Manager
now includes all of the QuickTime 2.5 extensions.

With this update, you also get the following enhancements,
which were available with System 7.5.3 Revision 2:

-  Better reliability for PowerBooks using RAM Doubler
If you have a PowerBook using system software 7.5.3 and you
use RAM Doubler (version 1.6.1 or earlier), you may have
experienced a problem when waking your PowerBook from
sleep.  This software fixes this problem.

-  Overall performance enhancements for PowerBook 2300
series and PowerBook 500 series computers with the PowerPC
Upgrade Card installed

-  Improved reliability when using PC-formatted floppy
disks with PowerBook 500 series computers with the PowerPC
Upgrade Card installed
If you have a PowerBook 500 series computer with the
PowerPC Upgrade Card installed, PC-formatted floppy disks
that were formatted on your computer may be unreadable in
DOS or Windows computers.  This software fixes this

-  Improved reliability on PCI-based computers and
PowerBook 5300 computers, PowerBook 2300 computers, and
PowerBook 500 series computers with the PowerPC Upgrade
Card installed

-  Improved reliability when copying files to some 1
gigabyte hard disks
If you have a PCI-based computer with a 1 gigabyte hard
disk, this software helps avoid problems when copying files
to the hard disk.

-  Improved reliability when using the Startup Disk control
In rare instances, when you turn on a PCI-based Power
Macintosh computer it may not start up from the disk
selected in the Startup Disk control panel.  This software
fixes this problem.

Important information regarding System 7.5.4 Update:

System 7.5.4 Update was released by Apple Computer to a
limited distribution, prior to an anticipated general
release.  Shortly after this limited distribution, an issue
with the software was found which required a revision. 
This revision was named System 7.5.5 Update. It replaces
System 7.5.4 Update and will install on computers which
have System 7.5.4 Update installed.

Copyright 1996  Apple Computer, Inc.  All rights reserved.