floppy tape-drive: an idea

DoN Nichols dnichols at ceilidh.beartrack.com
Mon May 27 09:46:32 AEST 1991

In article <1991May26.061914.9033 at umbc3.umbc.edu> ac999321 at umbc5.umbc.edu (ac999321) writes:
>       About a week or so ago, there was a thread about using a
>floppy tapedrive with a 3b1 and it was mentioned that hardware
>mods for a second floppy drive would be necessary in order to do
>this.  Wouldn't it be just as feasible to either:
>  a. Disconnect the present floppy drive and hook up a tape drive

	[ ... ]

>   b. Similar to 'a' above, only instead of having to physically

	[ ... ]

	I don't know about other floppy tape drives, but the one used in the
unix-pc uses the side-select line, and the drive-select lines to position
the head over the track of interest at the given instant.  These lines
aren't even connected to driver chips in the 3b1, except for the lowest
drive-select line and the side-select, which are used in the control of ONE
floppy disk drive.

	The floppy-tape drive is controlled by a floppy-disk controler CHIP,
with lots of strange logic around it to generate the combination of signals
required by the drive.  It, of course, needs a special loadable device
driver, while the floppy-disk controller chip is under the control of a
driver COMPILED INTO THE KERNEL, making it difficult to disable, so it
doesn't fight your own loadable driver for control of the chip.

	I think that any attempts to use the floppy-disk controller built
into the machine for controllng a floppy tape drive are just asking for
trouble, unless other floppy-tape drive interfaces are less likely to cause
problems when asked to share space with a floppy-disk drive.  (Something
which simply used the step-in and step-out lines to select track number, if
made, would be easier to interface, but it still would need to convince the
kernel to stop playing with the controller chip.)

	Good Luck

Donald Nichols (DoN.)		| Voice (Days):	(703) 664-1585
D&D Data			| Voice (Eves):	(703) 938-4564
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