[comp.sys.ibm.pc] 720 kB 5 1/4" floppies?

hst@mh_co2.mh.nl (Klaas Hemstra) (05/22/89)

from thomas@penet.UUCP (Thomas Aschan):
> Does anybody have experience with reading & writing 720 kB 5 1/4" floppies?
> I guess the BIOS should support the 720 kB format. I'm using a PHOENIX BIOS
> and i don't belive it is able to do this trick.

Hello Thomas, hello world (-: :-)

I am using 720 kB 5 1/4" floppies at home.
My system is a XT clone with a 30 Mb Harddisk and a TEAC 80 tracks floppy-drive
(DD, not HD) which can be switched from 40 to 80 tracks with a switch.
This system has a Phoenix Bios too.
It can read and write 80 tracks (720 K) floppies without any problems.
It can also read and write 800 K (!) diskettes formatted with a program from
this newsgroup without any additional TSR programs !

But on other systems my experiences with 720 K 5 1/4" floppies are not that
good.
- An early IBM AT (ROM date .. 1984) can not read them, the system thinks
   they are 40 Trk DD/DS so it outputs two track step pulses.
- An newer IBM AT (ROM date ... 1986) is able to read and write them.
- A Compaq 386 can not read them (not without DRIVER.SYS that is)
- A Tulip AT compact can read and write them without any problem  

I keep using them because of the double capacity, but I am not very content
with all those different systems that can not read my floppies.
I know that with DRIVER.SYS most problems could be solved, but I don't like
having a special boot floppy for reading or writing my 720 K floppies.

Secondly, the floppies formatted at 800 K can only be read and written at my
own XT, all other systems produce the strangest files and sizes.
The FALCON DOS (3.1) that came with my XT can also CHKDSK these 800 K floppies.
When you start CHKDSK it first reads the floppy and then says:
Probably NonDos disk, continue ?
Answering Yes to that question does the trick and it reports the floppy size
and contents correctly.

I hope this is of any use,

					Klaas Hemstra
Klaas Hemstra  (hst@mh.nl)                   |    /  / ,~~~  ~~/~~
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