mjg@ecsvax.UUCP (04/03/87)
Keywords: Fastback, Xenocopy, Lost Data, "Smart Disk Drives",
Check your drive out, Add to The Sum of Human Knowledge.
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Anyone who uses a program that accesses floppy disk drives
in a non standard fashion should be aware of the following compatibility
problem. Some drives are definitely too clever for their own good and
can affect the proper working of programs like Fastback.
The problem is this: Some drives develop a Drive Ready signal
which typically depends on ALL of the following being true:
1) The drive is powered on.
2) A disk is in the drive and the door or latch is closed.
3) At least two index pulses have been detected
4) The elapsed time between pulses is 200 mS +/- some tolerance.
Now the IBM PCs et al do no use the Ready signal so ordinarily
this would not be a problem. However some drives, (e.g. Canon and Teac)
gate the read and write data with the Ready signal so if the drive thinks
it is not ready then no data is recorded or read back. Programs like
Fastback will start sending data immediately the 1st index pulse is
detected BEFORE the drive is ready and recording is enabled. Lost Data City.
Yet other programs like XenoCopy ask you to cover the index hole on the
disk when reading some recalcitrant CP/M formats on your PC. Here the drive
NEVER becomes ready so disks can not be read with the index hole covered.
The Definitive Test
====================
Take a regular PC or MS-DOS disk and put it in the drive under test. Type DIR
and see what you get. Then take the same disk and cover the index hole with
an OPAQUE sticker such as a write protect tab. Type DIR and if you get the
same as before then all is well (You see, the PC does NOT rely on the index
hole for reading and writing - only for formatting). If you get an error
message then your drive is one of the bad guys. It may be possible to fix
it by changing jumper settings. In any case I would appreciate hearing from
anyone that tries the test so that I can compile a list of good and bad
and if there is interest, post it to The Net. Note that significant
differences exist between drives which sell under apparently the same type
code. For instance, I have already found substantial differences between
Teac FD 55F-03-U and FD 55F-06-U drives so if you can get the full part
number off the drive label it would be very helpful.
Please Email result, type of computer and disk drive to:
Mike Gingell, ....decvax!mcnc!ecsvax!mjg