Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!deimos.cis.ksu.edu!atanasoff!jwright
From: jwright@atanasoff.cs.iastate.edu (Jim Wright)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Hard Drive Characteristics
Keywords: heads, cylinders, FAT, llformat, format, partition, etc
Message-ID: <899@atanasoff.cs.iastate.edu>
Date: 23 Mar 89 09:29:44 GMT
References: <2369@lll-lcc.UUCP> <7313@thorin.cs.unc.edu>
Reply-To: jwright@atanasoff.cs.iastate.edu (Jim Wright)
Organization: Iowa State U. Computer Science Department, Ames, IA
Lines: 29

In article <7313@thorin.cs.unc.edu> davis@cs.unc.edu (Mark Davis) writes:
| Controllers of various types seem to be limited to:
| 	a. 20 Megabytes (very old, may be myth)
| 	b. 8 heads (somewhat old)
| 	c. 1024 cylinders (also somewhat old)
| I don't know specific controller combinations except the only 20 meg
| limit was very old IBM controllers.
| 
| In general, reasably modern (after 1982) controllers are not too
| limited, but be careful of the above limits.
 
You might be surprised, but this isn't really true.  IBM has been
selling these brain-damaged controllers quite recently.  Someone here
bought two of the last IBM PC XT's (the last model to be dropped other
than the XT-286).  The hard drive controllers in these were limited
to four drive types, 3 of about 20M and 1 about 10M.  These controllers
had to be junked to add an RLL drive -- the original controller would
not work at all in conjunction with a second controller.  So the upgrade
cost not only an RLL drive and RLL controller, but a new MFM controller
as well.

Remember, buy a computer, not three letters.  Who needs a hard drive
controller that locks you into a very few low-end drives?  Or a CGA
card that is incapable of resolving memory conflicts?  Or an EGA card
with only 64K of memory?  Or...

-- 
Jim Wright
jwright@atanasoff.cs.iastate.edu