Mac OS 7.5.5

Mac OS 7.5.5, also known as System 7.5.5, is a three-disk set of system software enhancements released on September 18, 1996 that delivers improvements in stability and performance for Apple Computer's own Macintosh systems as well as Macintosh clones.

The System 7.5.5 Update supports all Macs running Mac OS 7.5.3 or 7.5.4, and will result in the system software being updated to version 7.5.5.

Bug fixes

 * The floppy drive is now more reliable on Macs with DOS-compatible options (e.g. the Macintosh Quadra 610 DOS Compatible)
 * System startup now more reliable for 180 MHz or faster high-performance PowerPC 604 or 604e Macs
 * Improvements in the reliability of the remote control included with the Macintosh TV and Macs with Apple TV Tuner Cards.
 * One cause of Type 11 system errors were eradicated on PowerPC-based Macs.
 * Network made more trouble-free with the Macintosh Performa 5400 and 6400 series.
 * Data integrity enhanced when accessing a Macintosh Performa 5400 series system over the network.
 * More reliable use of sound-intensive application programs for Macintosh Quadra and Centris systems which have been updated with Apple's Power Macintosh Upgrade Card.
 * Performance improvements mainly involve virtual memory -- this includes dealings with large applications and accessing SCSI devices.
 * The Universal System Folder capability has been enhanced and updated to support the Macintosh Performa 5400 and 6400 series. This now allows people with Mac OS 7.5.3 to create a single system folder on an external hard drive or removable media and use it to start up all Macs from the Macintosh Plus to the Power Macintosh 9500 as well as all Mac clones.

System requirements

 * The System 7.5.5 Update installer requires at least Mac OS 7.5.3. Users of Mac OS 7.5.2 or earlier must first update to 7.5.3 before attempting to update to 7.5.5.
 * Bug fixes from all revisions to 7.5.3 are included in 7.5.5, making installation of 7.5.3 Revision 2, 2.1, and 2.2 unnecessary.
 * Users of Mac OS 7.5.4 may also directly update to Mac OS 7.5.5.

Notes to old Macs
Mac OS 7.5.5 is the last system software release for all remaining Macs based on the Motorola 68000 chips, as well as some other systems. These affect:

Macs with Motorola 68000 processors:
 * Macintosh Plus
 * Macintosh SE
 * Macintosh SE FDHD
 * Macintosh Classic
 * Macintosh Portable
 * Macintosh PowerBook 100

Macs with Motorola 68020 processors:
 * Macintosh II
 * Macintosh LC

Macs with Motorola 68030 processors: (not 32-bit clean)
 * Macintosh IIx
 * Macintosh IIcx
 * Macintosh SE/30

The reason for ending support for these Macs is that future system software releases require at least a Motorola 68030 with 32-bit clean ROMs. Subsequent Macs with Motorola 68040 and PowerPC processors contained 32-bit clean ROMs. The PowerBook 1400 is specifically not supported by this update. Users of PowerBook 1400 models are advised to skip to Mac OS 7.6 or later.