3 Jun
2004
3 Jun
'04
8:39 a.m.
From: "Roger Merchberger"
<zmerch(a)30below.com>
Rumor has it that Nico de Jong may have mentioned these words:
Ah, never say never, my friend! ;-)
I know little about 8" floppies, but I know that Apple ][ 5.25" drives
(which used GCR encoding, IIRC) could use hard or soft sector floppies. It
actually wrote an "index blip" (for lack of the correct term) on the disk
itself during format & used that instead of any physical hole(s) in the disk.
Hi
I also believe that one can use hard sectored disk in place of
soft sectored disk in most machines( of course formatted as soft
sectored ).
There is a difference between single and double
density that is related to the position of the index hole. My
understanding is that unlike the 5-1/4 disks, the 8 in. media
is the same for the single and double density, just higher
quality. In fact, I punch a new index window in some of my
double density 8 inch floppies and I've been using them, with
no troubles, as single density.
The 5-1/4 disk are a different story. Single/Double don't mix.
Dwight
I have a
DEC RX01 drive and the box of floppies that I have
with it are 8 inch single sided single density. Are 8" hard
sectored floppies compatible with these?
Hard and Soft sectored disks are never compatible. 
3 Jun
3 Jun
1:11 p.m.
On Thu, 2004-06-03 at 10:39, Dwight K. Elvey wrote:
density that is related to the position of the index
hole. My
understanding is that unlike the 5-1/4 disks, the 8 in. media
is the same for the single and double density, just higher
quality. In fact, I punch a new index window in some of my
double density 8 inch floppies and I've been using them, with
no troubles, as single density.
In the day quality and specs were such that it was foolish to use the
wrong media. Today you can pull that stuff. Using DD as SD should be OK,
but the converse will work "most" of the time, which is useless unless
you're just playing.
We used to pay $80 for a box of DSDD Dysan 8" floppies and align the
disk drives every year with a Dysan alignment diskette and an
oscilloscope. That's what it took for repeatable reliability. It sucked.
Process control is down pat these days. You can safely assume the
cheapest 5% tolerance resistors are very close to 1%; I assume Yaseo
makes only one kind of resistor ("1%") and the nifty machine sorts based
upon tolerance or the desired fraction of production is diverted for 1%
labelling or somesuch. It'd be hard to believe other things with graded
performance aren't handled the same way (not that you can buy "single
density" media any more!)
4:18 p.m.
On Thu, 3 Jun 2004, Tom Jennings wrote:
In the day quality and specs were such that it was
foolish to use the
wrong media. Today you can pull that stuff. Using DD as SD should be OK,
but the converse will work "most" of the time, which is useless unless
you're just playing.
There used to be a popular folk myth that all single sided diskettes
actually double sided ones that had failed testing on one side.
I find it hard to believe that any company could be profitable
with THAT high a failure rate!
We used to pay $80 for a box of DSDD Dysan 8"
floppies and align the
disk drives every year with a Dysan alignment diskette and an
oscilloscope. That's what it took for repeatable reliability. It sucked.
... and yet nobody was buying 8" Dysan alignment diskettes and new
shrinkwrapped Dysan floppies at $1 per diskette at VCF! My biggest
market segment was teachers who each wanted ONE diskette to wave in
the air when talking to classes about the days of dinosaurs.
--
Grumpy Ol' Fred cisin(a)xenosoft.com
5:34 p.m.
On Thu, Jun 03, 2004 at 06:18:00PM -0700, Fred Cisin wrote:
... and yet nobody was buying 8" Dysan alignment
diskettes and new
shrinkwrapped Dysan floppies at $1 per diskette at VCF! My biggest
market segment was teachers who each wanted ONE diskette to wave in
the air when talking to classes about the days of dinosaurs.
That's because I wasn't there...
I have a carton or two of RX01Ks, but nothing for my S-100 CP/M machine (I'd
rather not take a DEC-formatted floppy and overwrite it).
I have several 8" drives that aren't RX01s and RX02s (a TM848 in a DEC clone
with a 3rd-party Qbus card, a Heath H-27, and at least one DS440 or similar).
I haven't tried aligning any of them, but it wouldn't matter anyway, as I
have no alignment disks larger than 5.25".
-ethan
--
Ethan Dicks, A-130-S Current South Pole Weather at 04-Jun-2004 02:30 Z
South Pole Station
PSC 468 Box 400 Temp -87.5 F (-66.4 C) Windchill -112.8 F (-80.40 C)
APO AP 96598 Wind 4.1 kts Grid 076 Barometer 660.9 mb (11355. ft)
Ethan.Dicks(a)amanda.spole.gov http://penguincentral.com/penguincentral.html
4 Jun
4 Jun
1:41 a.m.
On Thu, 3 Jun 2004, Tom Jennings wrote:
There used to be a popular folk myth that all single sided diskettes
actually double sided ones that had failed testing on one side.
I find it hard to believe that any company could be profitable
with THAT high a failure rate!
I once worked in memorex in the tape plant where open reel tape was made
and that is exactly how it was done, raw tape was run through error
detecting
machines and sorted.
11:43 a.m.
On Thu, 2004-06-03 at 18:18, Fred Cisin wrote:
No, and you don't see people wearing onions around their neck anymore to
ward off illness either.
Man, like many others I used to do edits and huge (sic) compiles and
library building and linking, HOONK HOONK HOONK for hours, every day,
for however long an individual floppy lasted. (1.25MB each, seemed like
a lotta space at the time.) THAT ate up floppies and drives! I put
solidstate relays on the big AC motors and let them run down after some
idle period, that helped.
We used to pay
$80 for a box of DSDD Dysan 8" floppies and align the
disk drives every year with a Dysan alignment diskette and an
oscilloscope. That's what it took for repeatable reliability. It sucked.
... and yet nobody was buying 8" Dysan alignment diskettes and new
shrinkwrapped Dysan floppies at $1 per diskette at VCF! My biggest
market segment was teachers who each wanted ONE diskette to wave in
the air when talking to classes about the days of dinosaurs. 
3 Jun
3 Jun
9:10 p.m.
On Thu, 3 Jun 2004, Dwight K. Elvey wrote:
I also believe that one can use hard sectored disk in
place of
soft sectored disk in most machines( of course formatted as soft
sectored ).
No, you can't. Or at least with many side effects because the floppy
controller will see 33 index pulses (32 sector holes + 1 true index hole)
per revolution. When looking for a sector most FDCs abandon operation if
the sector has not been found after e.g. 5 revolutions i.e. 5 "holes" from
the diskette.
quality. In fact, I punch a new index window in some
of my
double density 8 inch floppies and I've been using them, with
no troubles, as single density.
It is always possible to format a DD disk to SD because the latter has a
similar bit density on the media.
The 5-1/4 disk are a different story. Single/Double
don't mix.
Of course they do. Single density refers to FM encoding, double density to
MFM (or M2FM). What you mean is SD/DD and HD don't mix because the
magnetic media as very different properties.
Christian
7387
days inactive
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6 comments
6 participants
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cc＠corti-net.de -
cisin＠xenosoft.com -
dickset＠amanda.spole.gov -
dwight.elvey＠amd.com -
ron.hudson＠sbcglobal.net -
tomj＠wps.com