floppy drive interface specifications

[Rene Tschaggelar]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Rene

 

[Fred Bloggs]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Yes, you should.

 

[petrus bitbyter]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Rene

Rene,

There has been an ECMA specification concerning this information. Ever had
it in my hands but can't find it anymore. Maybe yo can google for it.

petrus bitbyter

 

[Nico Coesel]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

A floppy drive doesn't understand commands. The signals to and from a
floppy drive are very basic. You'll need a floppy drive controller
chip to do something usefull with a floppy drive. A good starting
point is to look into PC style hardware. Depending on your
requirements, you might be able to salvage a controller chip from an
old XT or AT floppy controller board.

 

[[email protected]]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Not really an answer to your question, but I'd strongly recommend
considering some sort of flash memory card instead of a floppy for any
new application.

3.5" floppy disks are notoriously unrelable, not perhaps originally,
but because both the drives and the media have been cost optomized to
the point where they can't be reliable. You could buy a very high
quality drive, and still end up with a customer using dirt cheap media.
Plus they're big, they're magnets for dust, they're slow, they don't
sotre much, etc...

Only if trying to make a drop in replacement for an existing product
with a strong "tradition" around it would I think a mechanical floppy
drive would make sense, and even then I'd be tempted to push the
switch, if necessary lashing together some sort of legacy (parallel or
serial port) reader to work with older PC's.

 

[[email protected]]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Rene

I have the IBM tech ref for the original IBM PC and the PS/2. I could
copy the pages for you. It has the command set and the actual
schematics for the original PC adapter
My address is good

 

[Rene Tschaggelar]

Rene,

There has been an ECMA specification concerning this information. Ever had
it in my hands but can't find it anymore. Maybe yo can google for it.

ECMA appears to be linked to the C# language.

Rene

 

[Zak]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

Look for the wd1771/wd179x data sheets. There may be an even older
version that has an even better data sheet.

The drive interface has stuff like data in, data out (the host should do
the encoding/decoding), stepping pulses (to move the head), an indicator
when the head is on track 0, whenever the media rotates through its
index position. From there it is timing, reading sector marks, reding
the data (or switching to write to start writing).

The wd17xx equivalent should be on the system using the floppy drive.
The floppy drive is just a buch of motors with drivers and a head with
drivers and read amp.


Thomas

 

[Didi]

To connect a floppy to an embedded

system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

I can find the connector in my old projects from the 80-s,
I could plot them to a .gif or .pdf file for you - but I will
have to do some digging. Please make sure you want to
connect an old style FDD - it has no controller, you
need a NEC uPD765 or equivalent (well, there were
also other chips but this one made it through the years
in various IP forms), and write some code driving
heads/sides, implementing seek commands by counting
stepper pulses, etc. I did it twice during the 80-s, but
by todays standards this may seem too much work...
You may wish to consider one of these $15 or so
USB floppy drives they sell for notebooks, will definitely
be the easier to do option (I would guess they are like ATAPI
drives over USB, perhaps SFF-8070).
If you decide you really do need the schematics of my old
FDD interface which has the connector shown on it,
let me know and I'll start digging.

Dimiter

 

[Steve Sousa]

I tried the manufacturers and wasn't able to
find them there. The floppy drive interface
specifications. To connect a floppy to an embedded
system, I should have the pin descriptions, their
function and timing. How and what commands are
sent.

ftp://ftp.beg-buerkle.de/support/Hersteller/Floppy/FD235HF/FD235HF-A429.pdf
and the datasheet for the nec uPD765 and WD37C65 or other more recent
controlers should get you going.

Best Regards

Steve Sousa

 

[Rene Tschaggelar]

Here you have some in-depth specifications:
www.teac.de/dspd/downloads/datasheets/dl_fd05hf8630.pdf

5.25" and 3.5" doesn't differ interface wise.

Here's the pinout:
http://www.hardwarebook.net/connector/storage/internaldisk.html

Pay attention to these signals:
Select drive
Head select
Enable motor
Step direction
Step signal
Read data
Track-0

What is the objective .. ?

Thanks, that should start me going.
The objective is to create a floppy drive. Not a
magnetic one though

Rene

 

[[email protected]]

What is the objective .. ?

Thanks, that should start me going.
The objective is to create a floppy drive. Not a
magnetic one though

What would be the benefit of this one over what's already "out there" ..?

Beware that I haven't seen any floppy controller doing more than 2 Mbps.
Thus a lowend storage media (pc floppy controller is braindead ontop of that).

 

[joseph2k]

ftp://ftp.beg-buerkle.de/support/Hersteller/Floppy/FD235HF/FD235HF-A429.pdf
and the datasheet for the nec uPD765 and WD37C65 or other more recent
controlers should get you going.

Best Regards

Steve Sousa

Add the spec for an old 8277 or a more current 82077 for more complete CPU
interfacing options.

 

[Rene Tschaggelar]

What would be the benefit of this one
over what's already "out there" ..?

Beware that I haven't seen any floppy controller
doing more than 2 Mbps.
Thus a lowend storage media (pc floppy controller
is braindead ontop of that).

Let me think about that a bit longer.
I'll report back in due time.

Rene

 

[Mark Zenier]

Thanks, that should start me going.
The objective is to create a floppy drive. Not a
magnetic one though

Here's some stuff I dug up a few years back when I was thinking
about a project for an SPI interfaced floppy controller for
low end embedded projects.

There are ISO standards for the format, with specs for the CRC and
stuff like that, if you need to have the simulator interpet the
data stream (track/sector and stuff like that).

ANSI X3.80-1988 the physical drive interface, (some strange
obselete stuff in there). I got better information from the
National PC8477B super FDC controller chip datasheet.

ISO 7487/3 360 kbyte (MS-DOS) Double Sided Double Density disk format

ISO 8378/1 720 kbyte 5 1/4" disks media description
ISO 8378/2 seldom used standard format
ISO 8378/3 format used by MS-DOS
ISO 8630/1 1.2 Meg 5 1/4 inch media
ISO 8630/2 seldom used standard format
ISO 8630/3 format used by MS-DOS
ISO 9529/1 3.5 inch media
ISO 9529/2 1.44 Meg format

A couple of other items that look useful that are in my notes
are Motorola Application Note AN917 about their analog floppy
read/write ICs , and and article in Computer Design for February 1980.

The main wierdness that you'd have to deal with is that the controllers
predistort the timing of pulses to compensate for bit time shifts
caused by bit crowding on the media. So if your drive simulator amounts
to a dumb logic analyzer, (just saving the bit stream), you'd need to
compensate for this predistortion and then save each bit transition time
with a resolution of (SWAG) 10 nanoseconds or so. (The controller
derives the read timing with a PLL, so if the bit timing is too coarse,
it might FUBAR).

What happened to my project? Well, I copied all of my floppy media to
images on a CD ROM so I didn't need to read them again, and found in
doing that, (like another poster said), that 3.5 inch media are now such
crap that they're not longer worth the effort.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)