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From: Ralph.Hyre@IUS2.CS.CMU.EDU
Newsgroups: comp.sys.apple
Subject: Query: Apple Disk drive controller architecture(s)
Message-ID: <561745777.ralphw@IUS2.CS.CMU.EDU>
Date: Tue, 20-Oct-87 12:29:00 EDT
Article-I.D.: IUS2.561745777.ralphw
Posted: Tue Oct 20 12:29:00 1987
Date-Received: Wed, 21-Oct-87 23:22:37 EDT
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What are the options in connecting disks to controllers to
Apple // or Macintosh systems?

I know of 4 controller systems  I'd appreciate it if someone could fill
in the gaps:  Is this all thoroughly documented somewhere?  I'd be
happy to buy a book.

1) 'The Original' state machine thingie that Woz designed.

2) IWM - used in the Mac, //c and //GS.  A modern version of 'the original'
which can talk the 3.5 inch as well as 5.25 drives, even in 'IBM'
(NEC 765 disk controller) format.

3) Protocol Converter (//c and //GS?) not really a controller, but a
communications bus similar in principle to SCSI designed to talk to the
integral controller in the UniDisk 3.5.  A crippled version of this (no 
daisy-chaning of 5.25 drives) is what you get with the //e.  Sigh.  I'd
like to know whether or not the Apple //e crippling was done in hardware
or software.

4) SmartPort (//GS or on disk side of Protocol converter?)
[Is this another name for the Protocol Converter?]
It is claimed that if you have a 'smartport' drive (like the UniDisk
3.5) you can daisy chain large numbers (7 or 128) of ANY Apple drive
including Mac external drives and old Apple 5.25 drivers to the back
of it.

					- Ralph