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Re: HD20



Patrick Schaefer wrote:

David Empson schrieb:


The original ST506 interface (as used in the ProFile, for example) uses
two ribbon cables.  One is 34 pins, and is basically the same as the
floppy drive interface used in the PC.  The other is about 20 pins, and
carries parallel data to/from the drive.



Unfortunately Apple didn't use a MFM drive with ST506 interface for
their ProFile. They took only the Seagate ST506 drive mechanism (ST412
will work, too) and fitted it with their own analog board. This board
ist the only ECL logic circuit I ever met up to now.

ST506 drive and analog board are controlled by the Profile logic board
in a Disk II-like way (phi0..3, RD, WD, WE, and GCR recording).

Patrick


Yeah. I was gonna say sumpthin like that, but given that it's been since about '87 since I cracked open a profile, I was sure my memory was right after 15 years. As I recall, not two cables but one wide one came off the drive. Yeah, real st-405 or 412, but like Patrick says, apple replaced the board on the bottom of the drive w/ their own proprietary thing.