All right! and 1.2M floppies; HwNote05(is this where I say long?)

[Jan Isley]

On "All right! and 1.2M floppies; HwNote05", 
	jbm at uncle.UUCP (John B. Milton) writes:

>On the 1.2M floppy. Convergent cheaped out here and went with the 2797 rather
>than the 2793. The reason being that they got a Side Select Output pin. What
>they traded was an internal clock divide pin.
>...
>I suppose what one could do would be to permanently modify the FDC to do high
>density by just copying the stuff from the floppy tape. As long as you still
>have access to a system with a low density setup you could access low density
>disks. With a 1.2M disk you could mount the floppy on /usr/spool/news and
>expire once an hour :)

Yup, John, it didn't work.  Just tying the !5/8 pin to +5V hung the drive up.
I was trying the simple fix about the time you were posting this.  Having 
tried the simple stuff, I'll go for the soldering iron again in a few days.
This can work, it may or may not be easy (read: may or may not require use
of a scope to fiddle with to frequency to drive the floppy etc...) 
BUT...it will work.  The question is, is it worth it?

I can buy new name brand 1.2M drives all day long for $80 or so, the disks
cost about $0.75 each in bulk, more if you love to waste money.  So, you have
to buy a drive and the disks cost around 3 times as much as DSDD, but they 
hold 3 times the data.  AND, they may not take 3 times longer to read and 
write!  Want proof?  Next paragraph please.

I have had a Mac since 84 so I am used to the slightly higher price for those
cute little 3.5 inch disks.  Currently, I'm paying $11 to $12 for a box of 10.
If you are paying more, ask the sales person if it was good for them too.  What
does this have to do with unix-pc.general?  I have had a 3.5 inch floppy drive 
in my system for over two months now and it is working great.

Watch this:

iv -vt /dev/rfp020

Floppy disk
Volume Name: Floppy
80 Cylinders. 2 Heads per Cylinder.
There are 10 Physical Sectors (of 512 bytes) per Track.
	20 Physical Sectors per Cylinder, 1600 Physical Sectors per Disk.
There are 5 Logical Blocks (of 1024 bytes) per Track.
	10 Logical Blocks per Cylinder, 800 Logical Blocks per Disk.
The Floppy is Single density
The Step Rate supplied to the Controller is 0.
Partition 0: start Track=0, size (in Blocks)=5
Partition 1: start Track=1, size (in Blocks)=795
---------------------------------------------^^^ = 395 for an fdfmt10.nl disk!

Yea, 795k on a floppy that I can put in my pocket.  No, I have not timed it
with a stopwatch but it really does not seem to take any longer to format or
cpio to than a 5.25 inch disk.  1.2M drives are also lots faster than 360k
drives.  No, a 1.44M drive does not work for the same reasons as the 1.2M, 
I tried.  More to come on both drives.

Right now, the 3.5" drive is in the machine with a cable running out the back 
to the stock 5.25" drive.  I have a switch rigged on the floppy cable so I can
manually select which drive to talk to...not pretty, but effective.  This 
could be done up for a whole variety of floppy drives.

Now if someone wants to write a new gdisk for this thing, maybe we could have
more than 1 floppy working at a time.  Read in /usr/include/sys/gdisk.h:

#define DISKS		3	/* the number of disks on s4 */

Ouch!  We already know that 2 of those 3 are hard disks (thanks John!) There 
seems to be no mechanism for drive select in the software or hardware, but then
I am not a unix person (yet) anyway, it may be there and I missed it.  It sure
isn't in the hardware.  Anyone seen a drive select?

To use the 3.5" drives, just take the 5.25 drive out and replace it, simple.
Then you can add these files to help with formatting:

#--------------------
# /usr/bin/fdfmt35.nl
iv -i /dev/rfp020 /usr/lib/iv/FD35nl
mkfs /dev/fp021
dismount -f > /dev/null 2>&1

or for adding a loader, replace the first 2 lines with either of these:

#--------------------
# /usr/bin/fdfmt35.sl	<---silent loader
iv -i /dev/rfp020 /usr/lib/iv/FD35sl

#--------------------
# /usr/bin/fdfmt35.vl	<---verbose loader
iv -i /dev/rfp020 /usr/lib/iv/FD35vl

You may notice that these are just modified copies of /usr/bin/fdfmt??.??
And while you are copying files, add these in /usr/lib/iv/FD????

#-------------------
# /usr/lib/iv/FD35nl
# iv description for 3.5 inch 96 TPI Floppy file system disk w/o loader
type		FD
name		Floppy
cylinders	80 <--- we changed this to 80!
heads		2
sectors		10 <--- why can't this be more than 10???
steprate	0  <--- we cannot change this anyway
singledensity      <--- changing this is no help, to bad!
$
$
$
0
1
$
$

for the sl and vl stuff add these lines to the above:
#-------------------
# /usr/lib/iv/FD35sl
# iv description for 3.5 inch 96 TPI Floppy file system disk w/silent loader
#
#...same as above but change the last 7 lines to read:
#
loader		/usr/lib/iv/s4load.silent
$
$
0
7 <--- got to make more room for the loader here
$
$

#-------------------
# /usr/lib/iv/FD35vl
# iv description for 3.5 inch 96 TPI Floppy file system disk w/verbose loader
#
#... same as example #2 above but instead of s4load.silent, we add:
#
loader		/usr/lib/iv/s4load.verbose

If you use the user agent you could add the 3.5" selections to the menu if
you really want to take more time to format disks :-)

>Next time: 4M machine with a 1.5M Combo card (maybe)

Going to change the address select on a .5M expansion card???  Should make 
mine worth a few dollars more now |-) maybe I'll sell it.

Jan Isley, follower of Zen, picker of nit	h(404) 434-1335
jan at bagend.UUCP,  [...gatech...]!bagend!jan	w(404) 263-9200 ext4282
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