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Mad With Macintosh




Upgrade Your Classic II

to a LC 550

This Page Courtesy of John Stephens




This upgrade converts the Macintosh Color Classic to a Color Classic II which was only sold by Apple in Japan. It increases speed from 16mhz to 33mhz, allows an increase in RAM up to 36mb, 80ns from the standard of 10mb, 100ns, and increases VRAM to 512 from 256.


The conversion requires an LC 550 motherboard and a 72 pin SIMM, 2,4,8,16, or 32mb, @80ns or faster.


Make certain that the power switch is in the off position. Place the CC face down on a towel or other soft surface and disconnect all cables except for the power cable. The kitchen drainboard is a good place to work.


Plug the power cable into a three pin outlet. This grounds the chassis of the CC to earth and provides a discharge path for any static charge your body may have collected. At no time during this upgrade will you be in danger of shock but there is a very real danger to the motherboard from static electricity you yourself can generate when you move.


The rectangular plastic cover surrounding the plugs at the bottom of the case may be fastened with two screws. If so, remove them. Check again to be certain that the switch is off. Press down on the two plastic latches which project from the rectangular cover and lift the cover off the back of the case.


Grasp any of the protruding metal sockets and pull upward. The CC motherboard will slide out of the case. The power cord may now be removed. It effectively drained any static charge from your body when you grasped the metal on the outside of the sockets.


If you are working at the kitchen drainboard as suggested, touch a water faucet to make certain you have drained all residual static electricity. Prepare the LC 550 motherboard by installing the memory you have chosen. Slide the new motherboard into the opening from which the old motherboard. Re-attach the rectangular plastic cover which should snap in place.


Reconnect all cables, keyboard, mouse, power, etc. The Color Classic II is now ready to go.


On start up the screen remains dark for 30 seconds then welcome to Macintosh appears and the boot should complete in about 1min. 15sec..


John Stephens


Macintosh LC 550

aka Performa 550

This Page Courtesy of the LowEnd Mac




The 550 replaced the LC 520, bumping CPU speed from 25MHz to 33MHz.




introduced February 1994 at $1,200; discontinued March 1995

requires System 7.1 to 7.6.1

CPU: 33MHz 68030

FPU: 68882 (optional)

performance: 4.6 (relative to SE); 8.3 MIPS


RAM: 4MB on motherboard, expandable to 36MB using a single 80ns 72-pin SIMM; can use 1MB, 2MB,

4MB, 8MB, 16MB, or 32MB SIMM

video: 512KB VRAM, supports 640x480 at 8-bits

L2 cache: none

ADB ports for keyboard and mouse

DIN-8 serial ports on back of computer

DB-25 SCSI connector on back of computer

enhanced LC PDS slot

upgrade path: LC 575, Power Mac PDS card


Accelerators & Upgrades


Sonnet Presto Plus (33MHz 68LC040 or 68040, Ethernet, and 32MB additional RAM)


Special Resources

 Classic Mac Repair Tips

Email lists: Classic Macs Digest, Vintage Macs

Memory Upgrade Guide

AppleFacts Online for LC 550.

Read This Old Mac on the Mac Addict site.

Unix? You can run NetBSD (aka MacBSD), a version of Unix, on the LC 550.




Serial port normally restricted to 57.6kbps; use of a 56k modem may be limited. See 56k modem page.

For more information on Mac serial ports, read Macintosh Serial Throughput on the Macintosh Online

Technical Journal.



Some content used ith permission from Apple_history.com.

©1996-04 JagWerks Media




Some content used with permission from Apple_history.com.