Ethan Dicks wrote:
>I did spot the obvious format switch on the front of the disk unit, but no
>idea how to use it. I now wish that I'd picked up a couple more boxes of
>media from a friend's business about eight years ago. He had a pallet of 8"
>disks that he was selling for more money that I was willing to pay.
>Eventually,
>he gave me a case - my choice. I grabbed a 24" long box full of pre-formatted
>disks, the only one on the pile. When he disposed of the remainder, I didn't
>make a trip out there to grab any boxes. :-(
What part of the world are you in, Ethan? Here in North America, new
8" floppies (preformatted, even) are readily available from a number of
sources. Are you looking for small qty (less than 1000) or bulk
(qty greater than 1000)?
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
>Now if we take one media, standard 300o 5.25 twosided 96/100tpi certifed
>we are now talking about litterally hundreds of formats most of which are
>incompatable not by any reason of media.
That's why I stick to IBM 3740 (8", 77 track, 26 sectors/track, 128 bytes/sec)
format - guaranteed cross-platform compatibility! I can still read
my floppies from 1973 just fine...
All "real" machines have 8" floppies and at least one 9-track drive here!
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
On Oct 3, 16:56, Ward Griffiths wrote:
> Subject: Re: Floppy disks again
> Bill Yakowenko wrote:
> >
> > Hey, with the discussion of diskettes recently, and my own
> > search for info on RX50's, I was a little surprised by the
> > lack of available info on single-sided single-density 5.25"
> > floppy disks (emphasis on SD). Were they ever actually
> > manufactured, or was SS/SD strictly an 8" thing? I seem to
> > remember seeing SS/SD 5.25" way back when. Can anybody
> > give me an authoritative rating of their coercivity? Were
> > they 300 Oerstedts, just like DD? If so, what is it that
> > made them single density? Something about the size of the
> > individual magnetic domains maybe? Or were exactly the same
> > diskettes called "double density" when we figured out how
> > to make drives to handle that?
>
> Farzino, the Oersted value of SSSD (90k), DSSD (180k), SSDD (180k)
> and DSDD (360k) 5.25" diskettes was the same.
Those figures for capacity only apply to 40-track disks formatted with 9
sectors per track (IBM PC style). There are lots of other formats for
40-track disks, and of course there are also 35-track and 80-track drives.
> For that matter, it
> was the same with QD (720k) diskettes.
QD is a misnomer, it really means DSDD 80-track, and the figure of 720K
relates to 9 sectors per track, 512 bytes per sector.
Ignoring unusual techniques, such as GCR recording, as used by Apple and
Commodore, there are two possibilities for density in conventional floppy
disk systems. Single Density uses FM recording, and Double Density uses
MFM. They use the same number of magnetic reversals per track, but differ
in the way they include clock pulses, so MFM ends up with twice as many
data bits per track.
Then there are two possibilities fro number of heads, 1 or 2.
Finally, the number and size of sectors can be varied. IBM happened to use
9 sectors per track (8 on early systems, hence the existence of 320K disks
as well as 360K) with 512 bytes per sector, MFM. Other manufacturers did
not always use the same layout. Hence Acorn disks were usually 100K, 200K,
400K, or 800K (800K being 1024 bytes per sector, 5 s.p.t, MFM,
double-sided).
RX50 is MFM single-sided 80-track, 512 bytes per sector, 10 sectors per
track, giving 400K per disk.
> Manufacturers "tested" and
> rated the media for different densities, and I know that some disks
> that worked fine as SSSD failed miserable in the Tandy 2000 (720k)
> while others worked just peachy. I don't know of any failures
> involving using a higher-rated floppy in a lower drive except when
> the media had been previously used in a 720k drive.
That's not a density issue, merely a question of the width of the track
written by an 80-track drive as opposed to a 40-track drive.
> When you get
> to the official HD, 1.2Mb media, the situation changes.
That's right, the coercivity is different.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
>> When is 'for the time'? Torch (in the UK) released the XXX not that much
>> later (1984?). That was a _strange_ machine -- it ran unix (well,
>> uniplus+), and had a machintosh-like frontend.
Hmm, are Torch still in business? They used to be my local parts
supplier of of PC (Intel ;-) bits until a few years ago, and I
distinctly remember a pile of XXX systems that used to sit in the corner
of their workshop area - they may still be there for the taking if Torch
themselves are still around...
cheers
Jules
Hey, with the discussion of diskettes recently, and my own
search for info on RX50's, I was a little surprised by the
lack of available info on single-sided single-density 5.25"
floppy disks (emphasis on SD). Were they ever actually
manufactured, or was SS/SD strictly an 8" thing? I seem to
remember seeing SS/SD 5.25" way back when. Can anybody
give me an authoritative rating of their coercivity? Were
they 300 Oerstedts, just like DD? If so, what is it that
made them single density? Something about the size of the
individual magnetic domains maybe? Or were exactly the same
diskettes called "double density" when we figured out how
to make drives to handle that?
Also, my web search lead me to conclude that a 360K DS/DD
floppy should probably work okay as an RX50; the only
difference seems to be the number of tracks per inch. But
they write many times more bits per inch along a track (maybe
over 3000bpi?) than they do tracks per inch (48 vs. 96), so
the media itself must have high enough resolution. Are the
magnetic domains long and narrow and aligned radially? Or is
there some other reason that it gets less resolution radially
(tracks per inch) than longitudinally (bits per inch along a
track)? If the precision of the drive is the only limiting
factor, then DS/DD should work perfectly fine as RX50s.
Clues are welcome.
Cheers,
Bill.
Thanks Russ, that website looks like it might be useful!
What makes you think it is a 6286EL? I know next to nothing
about these AT&T boxes, so I never would have guessed anything
besides what it says on the label. Is it just because it's a
286 box? It quite definitely says "6300 PLUS" on the machine
itself and on all of the floppies that I got with it.
Cheers,
Bill.
On Thu, 30 Sep 1999, Russ Blakeman <rhblake(a)bigfoot.com> wrote:
] The AT&T setup files (in case anyone needs them) are located for download at
] http://www3.ncr.com/support/pc/pcdesc/library/63xx.shtml
]
] Me thinks he might have a 6286EL
]
] ...
I haven't been able to alter its power-up diagnostic sequence.
Tried holding down different function keys, escape, control-this,
control-that, blah blah blah... while booting. If there is a
BIOS setup program built in, I'd love to know how to wake it up.
It didn't even glance at the floppy drive during all of this, so
putting any particular disk into the drive seems unlikely to make
any difference.
Looks like maybe I'll have to warm up the soldering iron. Heck,
for that many chips, maybe the propane torch is more appropriate.
Bill.
On Thu, 30 Sep 1999, Glenatacme(a)aol.com wrote:
] In a message dated 09/29/1999 5:16:59 PM Eastern Daylight Time,
] yakowenk(a)cs.unc.edu writes:
] > Yesterday I scooped an AT&T PC 6300 Unix machine on its way
]
] Does this box have a BIOS setup program onboard or must you use a
] configuration disk? (if so do you have the disk?)
]
] I'd try turning off the parity check on the unlikely chance that the parity
] check itself is loopy . . . other than that, you've got a _lot_ of soldering
] to do ;>)
]
] BTW ISTR that one of our "customers" abandoned a 6300 in lieu of having it
] repaired. Contact me off-list if you're interested & I'll dig it out of the
] back room and check it out again.
]
] Regards,
]
] Glen Goodwin
] 0/0
I would like to buy a MicroBee machine, preferably
one running CP/M, but one of the earlier/smaller
BASIC ROM based models would be considered
also.
Roberto Waltman
rwaltman(a)bellatlantic.net
Thanks Bill,
I don't remember seeing DIP switches, but then I wasn't looking
for them either. I'll try digging info out of the NCR website
that Russ pointed out, and hope it tells me which switch is which.
Gosh, the machine on which the Korn shell was developed! Almost
historic, aint it? Hope I can get it to go. Wonder if ksh is
actually installed on it? :-)
Cheers,
Bill.
On Thu, 30 Sep 1999, Bill Pechter <pechter(a)pechter.dyndns.org> wrote:
] > The AT&T setup files (in case anyone needs them) are located for download at
] > http://www3.ncr.com/support/pc/pcdesc/library/63xx.shtml
] >
] > Me thinks he might have a 6286EL
]
] Sounds like a 6300+ to me... there was NO setup disk. Just dip switches
] like on the 6300's and XT's. There are no IBM AT compatible slots.
] Just Olivetti designed 16 bitters (this thing was designed before the
] AT Standard.)
]
] ...
and then, a few minutes later:
] > Does this box have a BIOS setup program onboard or must you use a
] > configuration disk? (if so do you have the disk?)
]
] Nope. No NVRAM either. Just a bunch of dip switches like an XT.
] Check the NCR web site for info.
]
] I had a 6300 and always wanted a 6300+. BTW, the story I heard is
] David Korn wrote the Korn Shell on a 6300+ for System V.
]
] It was used at AT&T as a single user development box for a while
] until the workstations began to appear as AT&T's Bell Labs moved from
] Vaxes and 3b's with BLIT's and 630 terminals to 7300's and later
] to Sun Workstations.
]
] ...
]
] Bill
] ---
] bpechter@shell.monmouth.com|pechter@pechter.dyndns.org
] Three things never anger: First, the one who runs your DEC,
] The one who does Field Service and the one who signs your check.
I've got a NCR Tower 32/500 (3466-500) running Unix that has a mixed-up
root password- see, I got it in working condition, with no password on
root. Like a dolt, I changed the password before setting up an account
for myself. It happily took the password, and I did an orderly shutdown.
Later, I re-started and went to log in, and it kept coming up with 'login
incorrect'. I did a disorderly shutdown (no way to log in to do it right)
and now it comes up in single-user mode saying it needs to be fsck'ed (no
problem), but it still wants a password. I've tried every convolution
of the password I used (it was a simple word, a numeral, and the # sign)
with no luck. I do not know any other accounts/passwords, nor do I have a
system install tape. Is there any way to get in without a password and
edit the /etc/.passwd file?
Richard
