Date   : Sat, 21 Apr 1990 18:19:01 GMT
From   : zaphod.mps.ohio-state.edu!rpi!crdgw1!ge-dab!tarpit!bilver!bill@tut.cis.ohio-state.edu (Bill Vermillion)
Subject: Cromemco WDI-II HDC Compatibility

In article <9004200703.AA12141@ucbvax.Berkeley.EDU> CUMMINGS@S55.Prime.COM
(Kevin J. Cummings) writes:
 
>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).

ST-506 and ST-412 interfaces ARE NOT THE SAME.

The 506 specs have write precomp.  The 412 doens't.  The 506 precomp line is 
is used in the 412 to switch to the other 8 heads.
506 can have 8 heads but no more, 412 can have 16.

This has been known to cause more than one person grief.


-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill@bilver.UUCP