Path: utzoo!attcan!uunet!husc6!bloom-beacon!mit-eddie!uw-beaver!teknowledge-vaxc!sri-unix!garth!phipps
From: phipps@garth.UUCP (Clay Phipps)
Newsgroups: comp.sys.ibm.pc
Subject: Hard Times Without A Hard Disk (Re: Mother board replacement?)
Summary: What hard disks are good with an inboard-386 in a PC-1 ?
Message-ID: <2301@garth.UUCP>
Date: 28 Dec 88 08:21:50 GMT
References: <1381@cps3xx.UUCP>
Reply-To: phipps@garth.UUCP (Clay Phipps)
Organization: INTERGRAPH (APD) -- Palo Alto, CA
Lines: 71

In article <1381@cps3xx.UUCP> jhl@frith.egr.msu.edu (John H. Lawitzke) writes:
>I am considering upgrading my current system. 
>I currently have a IBM XT 4.77MHz ...

I have comments that may be helpful, but close with *questions* of my own.

I am trying to upgrade my machine to support PageMaker and lots of 
I/O devices (e.g., scanners, disks) primarily for personal use 
on behalf of a volunteer nonprofit tax-exempt organization
(therefore, my employer indicated below has no reason to foot the bill).

>...any experience with motherboard replacement [versus] accelerator cards...?

I have a true-blue IBM PC-1 (4.77 MHz), whose BIOS I have upgraded
to the 1st true-blue IBM BIOS that supports a hard disk (Oct. 1983 ?).
I also have a Sigma Designs EWS-0000 expansion box, where most boards reside.
Were it not for the expansion box, I would have problems with adequate power, 
excessive heat dissipation, and slot shortages.

I chose to buy the intel inboard-386/PC board, 
which I was able to purchase for $750.
A large part of the reason was that I could keep my true-blue BIOS,
which should limit my compatibility problems to the inboard-386.
Its incompatibilities are not trivial, because the board requires 
a special version of, e.g., Windows-386, and will not run stock OS/2
(the former is now available from intel PCEO for $99[?]; the latter
is no problem -- I will install OS/2 when I install FORTRAN and COBOL :-).
I don't know anything about UN*X ports for the inboard-386.
I had only 320KB of system memory (including 256KB on an AST ComboPlus), 
so the 1MB on the inboard-386 is a welcome feature (2MB more can be added).

If I had a clone motherboard with a clone BIOS,
I probably would have decided in favor of a new motherboard, which 
would have gotten me 16-bit I/O, without risking much loss of compatibility.

What I gain is a 16-MHz 386 with 32-bit access to the onboard 1MB;	
what I don't improve is the 8-bit bus that I retain for I/O.
I expect that my extensive use of PageMaker will make far greater demands
on computation than on I/O (whether to screen or disk).

>...[On "]scrap the box and buy a new one ["] advice ...
>...I'm not...interested in investing an amount that...could buy a new car...

Obviously, I'm making drastic changes in my system configuration,
so the "buy a new one" advice makes some sense, even using my own money.
However, I will need very soon to replace a car with 178,000 miles on it.
I can't afford to spend too much on my computer system at any one time.
That argues very convincingly that I put in little improvements over time,
rather than waiting until I can afford a big-bucks upgrade all at once.
With incremental changes, I get an incremental increase in capabilities
that I can use right then and there.

Ultimately, this machine might be retired to BBS use, but no time soon.

*Questions*:
Are there limitations on the capacities of hard disks that can be run
on such a system ?  I assume that my system is a not-quite-XT for the 
purposes of selecting hard disks.  The XT doesn't have a disk-type table, 
unlike the AT, as far as I know.  I've read as much as I could find on 
disk selection, but have found no mention of limits; there must be some.
Are all of the gritty details handled by the controller ?  Which ones ?
Having an apartment that gets *very* warm in the summer, I am reluctant
to go with RLL's allegedly reduced margin for error relative to MFM.
Are there any disk access speeds that don't make sense for such a system,
providing performance that would be wasted by the 8-bit bus ?

-- 
[The foregoing may or may not represent the position, if any, of my employer]
 
Clay Phipps                       {ingr,pyramid,sri-unix!hplabs}!garth!phipps
Intergraph APD, 2400#4 Geng Road, Palo Alto, CA 93403            415/494-8800