Path: utzoo!attcan!uunet!wuarchive!mit-eddie!bu.edu!att!att!cbnewsm!cbnewsl!rl
From: rl@cbnewsl.att.com (roger.h.levy)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: SOME DRIVE TYPE QUESTIONS
Keywords: compuadd disk
Message-ID: <1990Oct27.211413.15998@cbnewsl.att.com>
Date: 27 Oct 90 21:14:13 GMT
Organization: AT&T Bell Laboratories
Lines: 28

About 2 years ago, I purchased a Compuadd 286/10 for a lab at work.
Although I ordered the 40 Mb disk option, the system appeared to be
delivered with a 30 Mb disk.  I tried to fdisk and made a few other
feeble attempts to search for an additional 10 Mb but other concerns
and a relative disk space surplus quickly made me forget this issue.
Last week, said computer suffered a CMOS parity error.  Having never
fiddled with CMOS (it was set by Compuadd), I rummaged around for
the system's documentation in order to find the drive type.  The disk
is a Miniscribe 3650 and the Miniscribe manual specified it as drive
type 3.  The prompts from the CMOS maintenance program indicated that
drive type 3 is 30 Mb (615 tr, 4 surfaces, precomp = 300).  Suspecting
that setting up the 3650 as this type was originally responsible for
my lost disk space, I scrolled through the drive type entries looking
for one that matched the 3650.  The only apparently matching entry
was drive type 32 (809 tr, 6 surfaces, precomp = 128).  After sel-
ecting this type, I was able to recover the long missing 10 Mb.
This leads me to ask the following questions:
   1. Are drive types standard?  Where is the definitive reference?
      Do they differ from bios to bios?
   2. Is the 3650 type 3 or 32?  Is the manual (type 3) or the bios
      (type 32) or both or neither correct?
   3. What affect did precomp = 300 rather than 128 have on my drive?
   4. Should I worry about the drive?  Can I rehabilitate it?  It
      seems to be working and I gave it a LL format with Spinrite.
Thanks in advance.

Roger Levy
rl@groucho.att.com