# Replacing floppy

G

#### George Jefferson

Jan 1, 1970
0
I have an old keyboard that uses floppy to hold its os. It takes about 3
mins to fully load if that. Also the disk can become corrupt overtime.

I was thinking of replacing the floppy with a ssd type of system. What I'm
thinking is possible is to "hijack" the floppy interface cable and simulate
a floppy disk but provide a faster system. Essentially emulating the floppy
disk protocol, which I imagine it uses some existing standard, but reading
off a ssd/eeprom.

Am I on the right track? Here the biggest problem is probably getting the
protocol correct and the electronics would be rather simple? Probably can be
done with a pic and not much more...

A

Jan 1, 1970
0
I have an old keyboard that uses floppy to hold its os. It takes about 3
mins to fully load if that. Also the disk can become corrupt overtime.

Ah, Musical keyboard. I was initially puzzling over what computer
keyboard would have such a need.
I was thinking of replacing the floppy with a ssd type of system. What
I'm thinking is possible is to "hijack" the floppy interface cable and
simulate a floppy disk but provide a faster system. Essentially
emulating the floppy disk protocol, which I imagine it uses some
existing standard, but reading off a ssd/eeprom.

How about trying a SmartMedia flash card and one of these -
http://en.wikipedia.org/wiki/FlashPath

J

#### John Tserkezis

Jan 1, 1970
0
Ah, Musical keyboard. I was initially puzzling over what computer
keyboard would have such a need.
How about trying a SmartMedia flash card and one of these -
http://en.wikipedia.org/wiki/FlashPath

This won't work, as it needs drivers installed first. I'm guessing
since the FDD is the only data storage interface available, this isn't
going to be an option.

On the little reading I've done so far, the situation can get quite
complex. There ARE floppy interfaces that supply USB, or CF flash
replacement storage devices, however, they are priced quite expensively,
from what I've read $500-$1000+ US, depending on features.

Also, I've read one person who had a similar problem with a musical
keyboard, where replacing the FDD with a standard PC model did not fix
the problem. True, we don't know if the problem wasn't with the disk,
however, there WERE various supplies of FDDs that appeared the same on
the outside, but the interface was at least a little different.

It would be wise to suggest really cheap options, as it would be rather
wasteful on the wallet otherwise.

N

#### Nico Coesel

Jan 1, 1970
0
John Tserkezis said:
This won't work, as it needs drivers installed first. I'm guessing
since the FDD is the only data storage interface available, this isn't
going to be an option.

On the little reading I've done so far, the situation can get quite
complex. There ARE floppy interfaces that supply USB, or CF flash
replacement storage devices, however, they are priced quite expensively,
from what I've read $500-$1000+ US, depending on features.

Also, I've read one person who had a similar problem with a musical
keyboard, where replacing the FDD with a standard PC model did not fix
the problem. True, we don't know if the problem wasn't with the disk,
however, there WERE various supplies of FDDs that appeared the same on
the outside, but the interface was at least a little different.

There are many ways an FDD can be controlled. Older floppy drives
usually have many jumpers to accomodate different controllers.

M

#### Mark Zenier

Jan 1, 1970
0
The serial protocol is either MFM or FM, NRZ code, with CRC added for
each sector.

Not NRZ. For both input and output, it's a short (100-300 ns) pulse
for each flux transition. For the input, inside the drive it's the
clock for a T flip-flop that (gated by the enables) drives the head.
For output, it's a one-shot triggered by a peak detector.

Mark Zenier [email protected]

M

#### Mark Zenier

Jan 1, 1970
0
I have an old keyboard that uses floppy to hold its os. It takes about 3
mins to fully load if that. Also the disk can become corrupt overtime.

I was thinking of replacing the floppy with a ssd type of system. What I'm
thinking is possible is to "hijack" the floppy interface cable and simulate
a floppy disk but provide a faster system. Essentially emulating the floppy
disk protocol, which I imagine it uses some existing standard, but reading
off a ssd/eeprom.

Am I on the right track? Here the biggest problem is probably getting the
protocol correct and the electronics would be rather simple? Probably can be
done with a pic and not much more...

If you want it read-only, fed by flash, it wouldn't be too hard.
A couple of outputs to fake the drive signals (index, track 0, etc).
Inputs for step, direction, drive enable, motor on, etc. The datastream
is documented in the floppy interface chip datasheet, or there are
various ISO standards for floppy formats that tell you enough information.

The main problem may be in reading in your original so you can save
it to flash. I suspect this may be one of those rare 3 inch Hitachi
hard shell diskettes. Few folks used them. Roland keyboards and the
Amstrad computers. (Sony won that battle with their higher capacity
3.5 inch diskettes). As I remember, electrically, the 3 inch drives
were the same as a double density (360kbyte) 5.25 drive.

There is (or was) a web site for a guy in Silicon Valley who had a unit
where you can replace the floppy drive (for various classic home compters)
and up and download floppy images from a PC. Search for "Semi-Virtual
Diskette" or "SVD".

Mark Zenier [email protected]

G

#### Grant

Jan 1, 1970
0
I think you are wrong:

http://en.wikipedia.org/wiki/Modified_Frequency_Modulation

<quote>
As is standard when discussing hard drive encoding schemes,
MFM encoding produces a bit stream which is NRZI encoded when written to disk.
A 1 bit represents a magnetic transition, and a 0 bit no transition.
<end quote>

I should know, I designed a multi standard floppy controller board,
and it works
It has one of the lowest error rates in the universe, ZERO.
Want the diagram?

I would like to replace the floppy interface in a TDS3034 DPO with some
USB or Ethernet interface.

Emulating a floppy is a possible method?

Would a PIC chip do that? Hang off the floppy drive cable, intercept
and interpret the signals? Make the DPO think it's talking to a real
floppy disk?

Grant.

G

Jan 1, 1970
0
A

#### Archimedes' Lever

Jan 1, 1970
0
I have an old keyboard that uses floppy to hold its os. It takes about 3
mins to fully load if that. Also the disk can become corrupt overtime.

I was thinking of replacing the floppy with a ssd type of system. What I'm
thinking is possible is to "hijack" the floppy interface cable and simulate
a floppy disk but provide a faster system. Essentially emulating the floppy
disk protocol, which I imagine it uses some existing standard, but reading
off a ssd/eeprom.

If you boot from an SSD, it appears as drive A: on some Motherboarss,
and drive C:" on others, and still others allow selection in the MOBO
BIOS as to how it gets treated.
Am I on the right track?

No. Just get the USB multi card reader. I installed Vista and W7 from
a mem stick onto a Revo, which has no floppy.

Also, if you boot DOS on a mem stick, it usually definitely shows up as
drive A:
Here the biggest problem is probably getting the
protocol correct and the electronics would be rather simple? Probably can be
done with a pic and not much more...
The data rate on a floppy interface bus is too slow, even if the 2.88MB
choice is used.

A

#### Archimedes' Lever

Jan 1, 1970
0
Yes that should be possible.

Chimes in Jan, with yet more guess as you go stupidity.

A

#### Archimedes' Lever

Jan 1, 1970
0
I should know, I designed a multi standard floppy controller board,
and it works
It has one of the lowest error rates in the universe, ZERO.
Want the diagram?

If it doesn't cover 2.88, it ain't worth a shit.

The data rate on the bus is too slow. Dump the idea.

A

#### Archimedes' Lever

Jan 1, 1970
0

At least you are smart enough to know that it is not possible on the
floppy bus.

A

#### Archimedes' Lever

Jan 1, 1970
0
On Tue, 27 Apr 2010 08:27:41 -0400, Jamie

J

#### Jamie

Jan 1, 1970
0
Grant said:
I would like to replace the floppy interface in a TDS3034 DPO with some
USB or Ethernet interface.

Emulating a floppy is a possible method?

Would a PIC chip do that? Hang off the floppy drive cable, intercept
and interpret the signals? Make the DPO think it's talking to a real
floppy disk?

Grant.
This is what you need

http://www.alibaba.com/product-free/107779005/Floppy_Drive_Replacement_Floppy_Emulator_Floppy.html

Etc. etc..

Have fun..

M

#### Mark Zenier

Jan 1, 1970
0
I think you are wrong:

RTFDS, I suggest one of the Western Digital floppy controller ones
like the 279x family. Or the MC3469, '70, '71 floppy drive electronics
ICs.
http://en.wikipedia.org/wiki/Modified_Frequency_Modulation

<quote>
As is standard when discussing hard drive encoding schemes,
MFM encoding produces a bit stream which is NRZI encoded when written to disk.

Er, you see the phrase "when written to the disk". Go look at an old
floppy drive schematic. (There's one in the original IBM PC Hardware
book, if you're as big a packrat as I am, or I could scan some others
that I have). You'll find that the write data line is used to clock a
T flip-flop, so what's in the cable is not what's on the disk.

A 1 bit represents a magnetic transition, and a 0 bit no transition.
<end quote>

I should know, I designed a multi standard floppy controller board,
and it works
It has one of the lowest error rates in the universe, ZERO.
Want the diagram?

Check and see if you've got a RC and Xor edge detector on
the write data line...

Mark Zenier [email protected]

G

#### Grant

Jan 1, 1970
0
If you ask me outright 'can a PIC do that?',
that would take a lot of investigation.
Much simpler is in my view to use one of the many dedicated floppy
controler chips *together with* a PIC.
I used the 8272A in the past (same as in the IBM PC).

Wrong end of floppy cable I want to emulate the floppy end of
the cable.

Grant.

J

#### Jamie

Jan 1, 1970
0
Archimedes' Lever said:
On Tue, 27 Apr 2010 08:27:41 -0400, Jamie

Well, that would explain why my virus scanner has been going
off a day early lately..

Thanks for the tip, window licker!

G

#### Grant

Jan 1, 1970
0
Sorry. I haven't been paying close attention to this thread. WHY do
you want to "emulate the floppy end of the cable"?

'cos floppies are so unreliable, and I have a borrowed instrument that
can dump screen images to floppy. Be nice to have a black box pretend
to be floppy but translate the dumped images to SD memory or something.

Options I have are emulating a parallel printer on a printer port, or
emulating the floppy drive. I don't have tech info on the internal
data bus for TDS3034 Don't have a much of a budget either.

It's been done, but they use programmable logic for USB interface, or
a very fast PIC chip for SD interface -- these are from a link posted
(I can provide data management circuitry... check my website.)

For which? Floppy interface or TDS3034?

Floppy interface is easy, translate serial data stream to/from memory
at an address block based on track number, sector? Pop out index marks
at suitable rate and respond to the step, dir, etc signals. How hard
can it be?

The old Ferguson BigBoard could read floppy drive with Z80 micro running
at 2.5MHz, without a controller. Nasty (tricky?) use of NMI to get the
response time for data transfer though.

Thanks,
Grant.

A

#### Archimedes' Lever

Jan 1, 1970
0
Well, that would explain why my virus scanner has been going
off a day early lately..

Thanks for the tip, window licker!

You were originally told by the Thompson tard or Terrell tard.

You were simply too much of a tard to have caught it.

S

#### SoothSayer

Jan 1, 1970
0
'cos floppies are so unreliable, and I have a borrowed instrument that
can dump screen images to floppy.

Floppies are fine if you do not rely on the 6x factory format that had
no error checking.

You MUST re-format, and fully format (not quick, if it is even
available) the disk. THEN check it for errors aside from the format's
standard check. THEN you can rely on it... a little longer.