Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!uflorida!gatech!mcnc!rti!bcw
From: bcw@rti.UUCP (Bruce Wright)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Old HD drives
Summary: The ST506
Keywords: oldies but goodies
Message-ID: <2816@rti.UUCP>
Date: 11 Mar 89 22:58:37 GMT
References: <2358@lll-lcc.UUCP>
Organization: Research Triangle Institute, RTP, NC
Lines: 70

In article <2358@lll-lcc.UUCP>, rzh@lll-lcc.UUCP (Roger Hanscom) writes:
> Does anyone out there remember the ST-506 (5M from
> Seagate)??  Are they reliable...junk...???  The reason
> I ask is I've been seeing them in surplus stores around
> here for $49.95.  I've been thinking about trying to
> use one on an older machine (I'd rather not spend big
> $$$ on it!).  What about an ST-605(or4??).  I saw a
> **BUNCH** of them in a surplus store labelled 6M.  I
> never heard of that number before.  Is there such a
> beast??

An ST506 is a slow, small, but -very- reliable drive.  Besides being
only 5MB it has an average access time of about 100ms or maybe a tad
more (I don't remember off the top of my head).  It uses the same
controller interface as the more recent drives (hence the name of the
standard XT hard drive interface -- ST506).  (This same interface is
used by many AT class machines as well ... though machines that are
trying for better performance typically use SCSI or ESDI or some other
scheme).

Now for the bad news.  The ST506 is -so- slow that many BIOSs are
unable to cope with it and time out thinking that the drive is dead
(this won't happen except in the worst case ... seek from the first
track to the last track or something close to that).  Even worse, it
doesn't support all of the functions of the more recent drives. (In
particular the buffered seek function).  It is likely to run on at 
least some compatibles (especially older ones running older copies 
of DOS that don't use all the functions of the BIOS) but it is 
certainly not guaranteed.

If you are willing to put up with a fair amount of hassle for a slow, 
small drive in order to save a few bucks, you should definitely get
some way to try it out on your system and see if it runs.  It will
be pretty obvious if the BIOS isn't happy with the drive, and shouldn't
damage the machine or the drive if it's done by someone who knows what
he's doing (!).  Unless you have an AT or an AT-like disk interface
you will need a hard disk controller which will set you back another
$50+/- ... you may be able to pick one up cheap at the same place, I
haven't priced low-end disk controllers lately (especially used ones).

I have never heard of an ST605 or ST604.  It's possible that they are
drives that never saw much use or that it's a typo for an ST506.

> While I'm asking crazy questions --- will PC Jr software
> run on a PClone??  What's the ticker inside a PC Jr -- the
> 8088???
> 
Maybe.  It depends on whether the software takes advantage of some of
the quirks in the PC-jr.  The basic processor and operating system are
the same (8088 and MS-DOS), but there were some video modes that were
unique to the PC-jr and also some differences in the sound generator.
The little plug-in modules are of course unlikely to run on anything
else ... I don't know of any other machine that supports them (although
it isn't a big problem in principle, there is still a section of the
PC address space dedicated to such plug-in modules and other similar
uses.  The problem is that unless you are willing to make modifications
to the hardware and maybe the BIOS of your clone, "in principle" and
50 cents will get you a cup of coffee).

Of course, if you have the interactive BASIC sources for the program,
you can just get GW-Basic or QuickBasic (the former is more compatible
with the BASIC on the IBM-PC and the PC-jr, the latter is -much- faster
and a bit more expensive.  All 3 BASIC's are Microsoft products) and
your problem is solved (possibly with a slight editing of the sources).

Why not just try it out?  It's -highly- unlikely to damage anything ...
and if it runs at all it will probably run -much- better on the clone
than it ever did on the jr!

					Bruce C. Wright