3.5" floppy drive question(s)

[Chuck Guzis]

On 11 Oct 2008 at 16:59, Phill Harvey-Smith wrote:

> Also depending on your system, it may require a ready signal on Pin 34, 
> most 1.44M drives supply disk change on this pin, however the couple of 
> systems I have worked with that require this signal (Amstrad CPC, 
> Spectrum +3), wiring the signal permenently to ground will do the trick.

And often cause the system to hang without a diskette in the drive, 
unless there's some sort of deadman timer on I/O operations.  There 
are also a few systems out there that have software to interrupt on 
ready-to-not-ready transitions to determine if a disk-changed 
condition should be checked for--but you mostly see this on systems 
with 8" drives with line-powered spindle motors.  We just polled the 
write-protect sensor on old 5.25" drives to do the same thing.

On many of those 34-conductor 5.25-3.5 adapters, the jumper for disk 
change switches between pin 34 and nothing.  A drive with a pin 34 
READY output on a PC that's expecting disk-change instead creates 
problems.  

Cheers,
Chuck






> 
> Note some of the older 1.44s may have jumpers to change the ID, and 
> enable ready. I have some Teac FD-235F drives that are like this (they 
> have a bunch of jimpers just to the left of the steper motor), 
> unfortunatly the HF that you have does not.
> 
> > Also, anyone know if there if it is possible to slow the spindle speed
> > so that 1.44M can be done on machines that only have DD data rate ?
> > (and if so, any of the above drives capable of being slowed ?)  Would
> > that even work ?
> 
> Unfortunatly I believe that the spindle speed in 1.44s is always 300rpm, 
> even when operating in HD mode, and that is fixed in the drive, I don't 
> think that's possible (with standard drives at least).
> 
> Cheers.
> 
> Phill.
> 
> -- 
> Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
> 
> "You can twist perceptions, but reality won't budge" -- Rush.