Date   : Fri, 20 Apr 1990 16:01:07 GMT
From   : zephyr.ens.tek.com!wrgate!copper!michaelk@uunet.uu.net (Michael D. Kersenbrock)
Subject: Cromemco WDI-II HDC Compatibility

       "Jim is asking about a disk controller that uses the ST-506
       INTERFACE, not about an ST-506 disk drive!  You may be a stickler
       for correct part numbers, but when you decide to flame someone,
       PLEASE understand what that person is talking about.  There are 4
       common disk drive interfaces today, ESDI, IDE, SCSI, and ST-506
       (also called MFM, also called ST412, etc, etc, etc)."

My understanding is that the ST412 is a buffered seek version of ST-506
which is why many controllers or disks may say ST506/ST412.  Most, if not
all, drives that called "ST506 interface" are really ST412 ones, but are
called ST506 for historical reasons.

Also, a drive with a ST506/ST412 interface can be running RLL encoding
as well (the drive itself really can't tell if it's RLL or MFM, only
it's controller knows for sure).

Dang young whippersnappers! Don't know computer history!  I remember
when I used to walk twenty bytes to school everyday, through chad-snow
twenty inches deep! ..... :-)

--
Mike Kersenbrock
Tektronix Microprocessor Development Products
michaelk@copper.WR.TEK.COM
Aloha, Oregon