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-   -   Rewire Laptop FDD as Replacement for Defective External FDD? (http://www.pcbanter.net/showthread.php?t=1111269)

[email protected] February 22nd 21 05:06 PM

Rewire Laptop FDD as Replacement for Defective External FDD?
 
Hi,

One of my old Gateway laptops (WinXP) uses an external (NOT USB
connected) FDD (could not find replacement) that is defective.

I have some good laptop FDDs, but different brand (from Thinkpad, etc.).

Is it possible for me (I was once a service tech, TVs, VCRs, etc) to
rewire the connector to use this other brand FDD?

Thank You in advance, John


Paul[_32_] February 22nd 21 09:33 PM

Rewire Laptop FDD as Replacement for Defective External FDD?
 
wrote:
Hi,

One of my old Gateway laptops (WinXP) uses an external (NOT USB
connected) FDD (could not find replacement) that is defective.

I have some good laptop FDDs, but different brand (from Thinkpad, etc.).

Is it possible for me (I was once a service tech, TVs, VCRs, etc) to
rewire the connector to use this other brand FDD?

Thank You in advance, John


The regular floppy cable is 34 wire, with interleaved ground.

http://www.interfacebus.com/PC_Floppy_Drive_PinOut.html

This looks about 60 contacts or so.

https://cdn11.bigcommerce.com/s-a1x7...=2?imbypass=on

Now, how do we figure out what's on the Gateway pinout ?
Why the extra pins ?

You expect some of the pins to be used for power for the
floppy drive, but that should take 4 or so pins.

I would recommend a USB floppy if you could find one, but
they're not functionally equivalent unless:

1) BIOS has boot code and "USB floppy as HDD" emulation code.
You can boot from a USB floppy, if your computer is
vintage 2005 or later or so. That's when USB boot and
a variety of emulations were added. Like booting off a
USB ZIP 250 for example (also looks like a 250MB HDD to the BIOS).

2) BIOS has config entry to disable floppy controller block.
When that happens, an external USB floppy becomes A:\ .
If you cannot disable the internal floppy block (which
is not a surprise really), then the USB floppy is assigned
a higher letter, which causes problems for booting FreeDOS
from the floppy or similar.

Doing it right, as you're doing, is commendable given the
vintage of the machine. But that pinout, with the pure crap
we have for search engines today, how will we find the machine
owner who has the web page for that ? The "pinout" websites
aren't likely to have that variant listed.

There are a lot of laptop schematics floating around the
web. There was a 9GB tarball of them for example. But even
so, there's probably 10,000 laptop designs out there, and
the schematic coverage won't be all that wonderful.

Paul

VanguardLH[_2_] February 22nd 21 09:51 PM

Rewire Laptop FDD as Replacement for Defective External FDD?
 
wrote:

One of my old Gateway laptops (WinXP) uses an external (NOT USB
connected) FDD (could not find replacement) that is defective.

I have some good laptop FDDs, but different brand (from Thinkpad, etc.).

Is it possible for me (I was once a service tech, TVs, VCRs, etc) to
rewire the connector to use this other brand FDD?

Thank You in advance, John


You can't open the external enclosure to replace the FDD inside of it?
Else, you'd have to map the 25 pins on the parallel connector to the
wires to see which ones were used for which purpose inside the case.
Just because they used a standard port layout doesn't mean they didn't
use a proprietary wiring setup inside the case. They could've made the
FDD wireing proprietary to their driver's support, like deliberately
screwing with the data out pins as to which order the FDD used.

If the FDD uses an IDE connector, that is a 16-bit bus versus the 8-bit
for the parallel port, so the driver would have to buffer for double
reads or writes.

Probably should open the case to see what interface the FDD inside uses.
There were also 50-pin SCSI FDDs, too.

VanguardLH[_2_] February 22nd 21 09:53 PM

Rewire Laptop FDD as Replacement for Defective External FDD?
 
VanguardLH wrote:

wrote:

One of my old Gateway laptops (WinXP) uses an external (NOT USB
connected) FDD (could not find replacement) that is defective.

I have some good laptop FDDs, but different brand (from Thinkpad, etc.).

Is it possible for me (I was once a service tech, TVs, VCRs, etc) to
rewire the connector to use this other brand FDD?

Thank You in advance, John


You can't open the external enclosure to replace the FDD inside of it?
Else, you'd have to map the 25 pins on the parallel connector to the
wires to see which ones were used for which purpose inside the case.
Just because they used a standard port layout doesn't mean they didn't
use a proprietary wiring setup inside the case. They could've made the
FDD wireing proprietary to their driver's support, like deliberately
screwing with the data out pins as to which order the FDD used.

If the FDD uses an IDE connector, that is a 16-bit bus versus the 8-bit
for the parallel port, so the driver would have to buffer for double
reads or writes.

Probably should open the case to see what interface the FDD inside uses.
There were also 50-pin SCSI FDDs, too.


I take it there are no free drive bays to install an internal FDD in the
computer case.

[email protected] February 23rd 21 01:13 PM

Rewire Laptop FDD as Replacement for Defective External FDD?
 
You can't open the external enclosure to replace the FDD inside of it?
Else, you'd have to map the 25 pins on the parallel connector to the
wires to see which ones were used for which purpose inside the case.
Just because they used a standard port layout doesn't mean they didn't
use a proprietary wiring setup inside the case. They could've made the
FDD wireing proprietary to their driver's support, like deliberately
screwing with the data out pins as to which order the FDD used.

If the FDD uses an IDE connector, that is a 16-bit bus versus the 8-bit
for the parallel port, so the driver would have to buffer for double
reads or writes.

Probably should open the case to see what interface the FDD inside uses.
There were also 50-pin SCSI FDDs, too.


I take it there are no free drive bays to install an internal FDD in the
computer case.


Hi Vanguard,

No drive bay for internal FDD.

Solution for Now:

I was able to use a USB connected external Dell FDD, that I use with my
Thinkpad T23 laptop, on this Gateway laptop.

Thanks again to you and Paul for all that information, John





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