Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!zaphod.mps.ohio-state.edu!wuarchive!texbell!merch!cpe!hal6000!trsvax!uhclem
From: uhclem@trsvax.UUCP
Newsgroups: comp.sys.tandy
Subject: Re: Replacing a Hard Disk on a 16B/6000
Message-ID: <193300194@trsvax>
Date: 21 Dec 89 16:23:00 GMT
References: <2968@cbnewsj.ATT.COM>
Lines: 63
Nf-ID: #R:cbnewsj.ATT.COM:2968:trsvax:193300194:000:3254
Nf-From: trsvax.UUCP!uhclem    Dec 21 10:23:00 1989


<>
B>I have a problem similar to one I saw reported earlier.  I have a 16B that
B>has been upgraded to a 6000(PAL changes).  I wanted to replace the hard
B>disk I am using.  Currently I have a ST225 that works fine.  I want to
B>replace it with a CDC 86 meg drive.  I have been told the drive uses
B>the ST506 interface and is rated at 28ms.  When I try to format the
B>drive I get the error message "drive not ready".  When I put the drive

If the drive has more than 8 heads, you will only be able to use 8
heads.  In addition, you must tape pin 2 on the "Control" cable on the
drive.  (That's the 34 pin cable that goes to every drive.)  You
sometimes have to do this on drives that have 8 or less heads anyway as
the drives really have a ST412 interface (only difference is pin 2) and the
electronics may honor pin 2 (Head select 2^3) even if the drive doesn't
have that many.  Standard chips, you know.

If the drive has more than 1024 cylinders or an abnormally high step
time (NOT seek time), you might have to start the format twice in a row
(DO NOT RESET between attempts) to get the heads all the way back to
cylinder 0.  If the format runs for a moment or even several minutes and
then reports it is not ready, cover pin 2.   Nearly 100% of the drives made
since 1985 with ST506 interfaces really have ST412 interfaces.  The
manufacturers apparently thought no one could cope with a different number.
The IBM AT hard disk adapter (including the original from 1985) uses ST412.
On early models there was a strap you changes if you really had a yucky old
ST506.  Nowdays I don't think they bother.   Line 2 was Reduced-Write-Current,
which nearly all drives with microprocessor control can determine for 
themselves and in ST412, the line is used to select additional heads (>8).

If you have a copy of TRSDOS for the Model II/16 laying around, boot it, 
run debug and do this:   (Sorry, the TRSDOS-II BASIC does not have IN/OUT.)
	OUT to port 0xc0 0x0c	(enable port)
	OUT to port 0xce 0x08	(512 byte sectors, Drive 0, Head 0)
	IN from port 0xcf	(read status port)

If the value you read is 0x50 or just has Bit 6 on, the controller believes
the drive is READY.  Bit 4 indicates the SC (Seek Complete) line is high,
another good sign of a properly connected drive.

If you want to try a restore,

	OUT to port 0xcf 0x1c	(restore to cyl 0 at 6.0 msec step)
	IN from port 0xcf	(read status port)

Depending on where the heads are, it may take some time for that command to
complete.  (Bit 7 in 0xcf is on when the controller is still working on it.)
When it does complete, you should read 0x50.  This indicates that a
good part of the drive and its host interface are working.

<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
 Shack/Tandy Corp has no obligation to support the information provided
 in  any way.  It just happens to work that way and its in the technical
 manual.>
						
					"Thank you, Uh Clem."
					Frank Durda IV @ <trsvax!uhclem>
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