NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/sys/3b1/4173

Internet Message Format | 1993-01-05 | 3.3 KB

Path: sparky!uunet!caen!rphroy!albert!rhaar
From: [e-mail] (Bob Haar)
Newsgroups: comp.sys.3b1
Subject: Re: Cable (and other details) for 720/800K flop
Message-ID: <[e-mail]>
Date: 5 Jan 93 12:59:44 GMT
References: <[e-mail]>
Sender: [e-mail]
Reply-To: [e-mail]
Organization: G.M. Research Laboratories
Lines: 77
Nntp-Posting-Host: albert.cs.gmr.com


In article [e-mail], [e-mail] (Kris A. Kugel) writes:
|>A couple of Questions for anybody who's put
|>a 720 K floppy on their 3B1/7300/unixpc:
|>
|>I'm attempting to attach a 720K floppy drive
|>to one of the 3B1's I've got here.  This has been
|>done before, and documented in comp.sys.3b1.
|>

Kris,

I assume that you are replacing the stock 5 1/4"
floppy drive with a 3.5" drive.  [Note that you can
have both drives hooked up to the system if you use
a manual switch to toggle the drive select line. I
do this with my 7300.]

|>Now, I'm wondering, what kind of cable do I buy?
|>The cable I've got goes from two rows of pins to
|>an edge connector, but the connector on my 720K
|>floppy drive is also two rows of pins, like the
|>connector on the motherboard.

As you noticed, the 5 1/4" drives use a different
connector than the 3.5" ones. I remember that the power
supply connection was also different.

|>
|>I'm assuming that it's a pretty standard part,
|>but I don't know if there are any special cable
|>twists needed, or what.
|>

What I did was to use a kit for mounting 3.5" drives
in a 5 1/4" form factor cabinet. This kit included
a power supply adaptor cable and a small circuit board
that plugs into the two row pin connector and brings out
the signals to an edge connector. If you do this, you can
use the stock cable.

You should be able to be buy an appropriate cable that
connects directly at any store that handles PC-clone
components. Don't confuse them by asking about a UNIXpc,
just say that you want a cable to connect a 3.5" floppy
drive to a controller.

|>Meanwhile, there didn't seem to be anything in
|>the literature sheet I got from Panasonic about
|>how to make the floppy drive operate only in 720K mode,
|>is there anything special I should do, and if so,
|>what am I looking for on the options sheet?
|>
|>Are there particular options I'm trying to set besides that?
|>If anybody is REALLY knowledgable, this is a Panasonic JU-257,
|>has an "AT&T" label on it too.

Sorry, I don't know the details of this drive. I used a Teac
in my system. However, if this is a HD drive (1.44 Mb capacity) that
you want to use as a 720K 2D drive, you may run into problems.

Also, did you know that you can use a 720 floppy drive in
10 sector mode and get 800K on it (just like the 400K,
10 sector format for 5 1/4" floppies). You cannot use this
format to interchange data with IBM PC's or Sun workstations,
but it is useful for system backups.

In any case, you will need some additional iv format descriptors
if you want to format either 720K or 800K floppies on your UNIXpc.
I can e-mail you my versions. Drop me a note if you want them.

      Robert Haar               InterNet : [e-mail]
    Computer Science Dept., G.M. Research Laboratories
DISCLAIMER: Unless indicated otherwise, everything in this note is
personal opinion, not an official statement of General Motors Corp.