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Path: utzoo!mnetor!uunet!husc6!rutgers!mtune!codas!burl!clyde!feg
From: feg@clyde.ATT.COM (Forrest Gehrke)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Sperry(?) DOS Problems
Message-ID: <12055@clyde.ATT.COM>
Date: Sun, 9-Aug-87 13:51:55 EDT
Article-I.D.: clyde.12055
Posted: Sun Aug  9 13:51:55 1987
Date-Received: Sun, 9-Aug-87 23:06:05 EDT
References: <116@dalcsug.UUCP>
Organization: AT&T Bell Labs, Whippany, NJ
Lines: 29
Keywords: Sperry,MS-DOS
Summary: Sperry----and Leading Edge Model M

In article <116@dalcsug.UUCP>, dalegass@dalcsug.UUCP (Dale Gass) writes:
> At work, we're having some problems regarding Sperry's Implementation of DOS...
> 
> Although generic MS-DOS 2.11, 3.1, and 3.2 will boot and run perfectly on
> the sperry PC-HT and PC-uIT, problems occur when using diskettes written under
> sperry DOS with MS-DOS.
> 
> I'm interested in finding out just what differences Sperry made in their version
> of DOS.  This only one I really could see and expect was a CLOCK` driver which
> kept the real time clock correct.  Here are some of the symptoms:

I am replying on the network in hopes of eliciting information from others, but
will email to you directly with further questions and information more detailed.
First of all, the Sperry HT (I believe also known as model 100) is identical to the Leading Edge Model M (both made by Mitsubishi).  The current L.E. PC is the Model D made in Korea and is not the same at all.  
The major difference of the DOS versions between the Sperry HT and the IT are
that the boot record for the IT version was placed in the same location in
sector 0 as it is in all other ms-dos versions, instead of immediately after
the jmp instruction at the beginning of the boot loading program.  This,
among other things, requires a ROM BIOS change.  The other major change, is
the one you noted: the RTC coding is different.  
I also noted the extremely slow floppy disk accesses of the IT version of
DOS when run on the L.E. Model M and have guessed this is due to some
coding differences involving the 1.2 mb floppy drives, but this is only
speculation.

I welcome any other inputs from people on the net who may have found
a solution to the excruciatingly slow floppy disk read problem.

Forrest Gehrke