Ref: 10710060
Title: Hard drives for Mac 512K's
Date:  7/7/88

Copyright 3Com Corporation, 1991.  All rights reserved.

A SCSI disk cannot be added to a Mac 512K, as it does not have a
SCSI port.  Only the Mac Plus and SE have the SCSI port.  You have
three options for adding a hard disk:

- Apple HD20 disk, runs off of an external disk (floppy) port.  The main
advantage is that you KNOW that all software will support it, and that
Apple will continue to support it as
it upgrades the operation systems.  Not significantly slower than a SCSI
drive (i.e. Apple HD20 SC, which runs on Mac Plus and Mac SE with their
built in SCSI interface).

- Third party hard disk, runs off of either serial port.  Advantages are
that the disk is cheaper than the Apple HD20.  Disadvantages are
substantial. Each company writes a driver that interfaces their disk to
the Mac operating system (finder and system files).  When Apple changes
the operating system files, which is regularly, you must go to the disk
manufacturer for an updated disk driver file.

- Internal hard disk.  Companies like General Computing have modified
Macs to accept an internal drive.  Apple has ok'ed the GC drives, and
most dealers can install and service these.

I recommend finding a used Apple HD20 drive, and having an Apple dealer
or a knowledgeable Mac technician check it out.  Prices on new HD20s should
be cheap, because most people are opting for the HD20 SC models.
