Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!amdcad!sun!pitstop!sundc!seismo!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Hard Disks: XT vs. AT
Keywords: hard disk xt at
Message-ID: <11517@steinmetz.ge.com>
Date: 13 Jul 88 14:50:47 GMT
References: <6201@megaron.arizona.edu>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 34

In article <6201@megaron.arizona.edu> cjeffery@arizona.edu (Clinton Jeffery) writes:
| Hi people: for a year now I have been running an Atasi 3046 drive in my
| XT clone.  Recently I purchased an AT clone kit, planning on using the
| Atasi as its hard drive.  So far, the hard disk "fails initialization"
| and has resisted any attempts at low-level formatting in the AT.

  I believe that AT disks are *not* ST506, they are ST412. The
difference in the two standards is that seek commands are buffered for
ST412 and the wait comes at the end.

BIOS commands to step five tracks:
	ST506		ST412
	
	step		step
	wait		step
	step		step
	wait		step
	step		step
	wait		wait
	step
	wait
	step
	wait

  Looking at the standards as presented in a short article I found, this
apperas to be the only difference, but it's enough to make the ROM BIOS
on the disk controller not work.

  Warning: this is my understanding of the matter, but I don't sell or
service disk drives.
-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me