3.5" floppy jumpers

Pete Turnbull pete at dunnington.plus.com
Fri Nov 28 02:57:19 CST 2008

On 28/11/2008 04:39, Curtis H. Wilbar Jr. wrote:

> Another is a TEAC FD-235HF and has jumpers for: H HO, OP, LHI, HHI,
> and a position (but no header pins) for FG.

See if Google can find you a document called 3fd0020a.pdf -- that's 
TEAC's config sheeet for the whole FD235 range.  There are lots of 
models with different jumpers.  That one is one of the dual 720K/1.44M 
3xxx (old) versions.

HO determines whether it outputs a signal to tell the host controller 
whether the disk is DD or HD, normally on pin 2.

HI determines whether it accepts a density select input on pin 2.

LHI and HHI are something to do with the density select input on pin 2. 
  They're definitely related to HI, but I seem to recall having jumpers 
on all three on at least one drive.  I'm pretty sure you jumper both or 
neither, never just one.

I'm not sure what H on its own would be.  HA tells the drive to 
determine density itself, from the HD hole sensor, instead of getting it 
from the host.

Sometimes there's a number after the jumper name, like for DC.  DC34 
means the Disk Changed signal is on pin 34, while DC2 (on a few models) 
means it puts that signal on pin 2.

FG is for Frame Ground; sometimes there's a jumper or solder link to 
connect it to the 0V DC supply.

> The last is a Sony MPF520-1 which has 2 rows of 3 pins... and I have
> no idea what they are for.
> I understand some abbreviations... RDY (ready), DC (disk change),
> but not MD, MM, TTL/C-MOS (assuming this is for interface logic
> levels?), and the TEAC ones I don't know at all.

MD and MM usually refer to what turns the motor on: only when asserted 
with Drive Select, or any time the Motor On signal is active.

> The Sony one is a mystery, and a google search hasn't turned
> anything up... don't know if the headers are for selecting D0-D3
> only... or more than that.

Some Sony drives have jumpers to determine when they output index pulses 
(only when the drive is up top speed, or always).  But if you only have 
a few, they're probably just the drive select jumpers.

Pete						Peter Turnbull
						Network Manager
						University of York

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