Using a 1.44MB 3.5inch floppy on an old controller

From: Michael Brutman <mbbrutman_at_chartermi.net>
Date: Sun Apr 22 13:33:35 2001

And to think that I've been worrying about finding thos 720KB
drive. It looks like I don't need them.

I know that the drive senses the media and adjusts the write
current accordingly, to get around a bug in older drive
controllers. But I'm still confused about how the drive
talks to the controller. The PCjr will still try to format
a HD disk - it will just fail.

I'm not a hardware engineer, but it would seem reasonable to
me that the controller and the drive always talk at the 250KHz
rate, because the controller can't do anything else. For
double density media this is fine, and the 1.44MB drive looks
and smells just like a real 720KB drive. However, upon using
a high density disk, commands to read and write data fail
because the drive knows it has high density media, but it is
still talking to the floppy controller at 250KHz (instead of
500KHz).

Is this correct? Or does the drive sense that it has
high density media, adjust it's data transfer rate to 500KHz,
and then fail because the controller doesn't know what's
going on?

While we're on the topic, what do people use for archiving
copy protected disks? I've tried older versions of TeleDisk,
but it really has a hard time with Sargon III which makes me
wonder if it is working reliably on my other titles.


Thanks,
Mike
Received on Sun Apr 22 2001 - 13:33:35 BST