"..The laptop must support floppy protocol through the LPT port for this to work.."
Is there any easy way to tell a laptop support it or not?

sangokushi wrote on 2025-02-17, 00:38:

"..The laptop must support floppy protocol through the LPT port for this to work.."
Is there any easy way to tell a laptop support it or not?

For the Sharp PC-9030 there are options for it in the bios. It is also listed and described in the manual. I am not sure how common this was to implement, or if it was a particular chipset configuration that allowed for this. I think it would be strange for Sharp to take the time to develop just for themselves. I also wonder if this is an option on other Sharp laptops from that era?

Some time ago Adrian's Digital Basement did an unboxing of a new in box laptop that I thought had a near identical look and spec to the Sharp PC-9030. This lead me to think that it was branded from something generic, or had licensed out clones of it. So I have some hope that it might have some compatibility outside of the Sharp series.

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is very different from the one used in your Sharp.

In a normal parallel port, pins 18 to 25 are always used as ground. However, looking at the schematic, we can see that in the Compaq pins 21, 22 and 25 have special functions

EduBat wrote on 2025-02-17, 21:18:

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is ve […]
Show full quote

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is very different from the one used in your Sharp.

In a normal parallel port, pins 18 to 25 are always used as ground. However, looking at the schematic, we can see that in the Compaq pins 21, 22 and 25 have special functions

I think it will be the same for the Compaq Armada series of laptops which all , afaik, have the ability to connect the floppy drive to the parallel port.
Are the schematics easily available on the interwebz?

weedeewee wrote on 2025-02-17, 21:44:

EduBat wrote on 2025-02-17, 21:18:

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is ve […]
Show full quote

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is very different from the one used in your Sharp.

In a normal parallel port, pins 18 to 25 are always used as ground. However, looking at the schematic, we can see that in the Compaq pins 21, 22 and 25 have special functions

I think it will be the same for the Compaq Armada series of laptops which all , afaik, have the ability to connect the floppy drive to the parallel port.
Are the schematics easily available on the interwebz?

The way I found the schematic for my laptop was by dumping the BIOS and looking for text strings. In there, I found a string saying fenway 2. So I looked for compaq fenway 2 on the internet and found the schematic on some open web forum.

EduBat wrote on 2025-02-17, 21:18:

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is ve […]
Show full quote

My Compaq N610c came with an adapter that allows the use of the parallel port with the floppy drive. However, the solution is very different from the one used in your Sharp.

In a normal parallel port, pins 18 to 25 are always used as ground. However, looking at the schematic, we can see that in the Compaq pins 21, 22 and 25 have special functions

Digging around I found this Compaq Armada service manual http://tim.id.au/laptops/hp/compaq%20armada%201500.pdf which shows this pinout table for the parallel port.

It seems like it might correlate to what you are talking about although we might need to investigate exactly how those extra pins work. It seems to me when pins 21 and 25 make a connection to the floppy drive then it sends 5v out of pin 25. Unfortunately the table does not include the floppy drive data pinout so we will have to search around for those. I think chances are slim that they would match the Sharp pinout, but maybe?

If this is common on many Compaq laptops it would be nice to build out a working adapter for it.

With the Armada series external drive I found this thread Compaq FDD on parallel port - How to make it work? that shows the drive opened up. It seems that the drive can be removed and the cable detaches. It might be possible to figure out the pinout with a multimeter.

Looking at the image I posted earlier and this one we can see that pin 21 is connected to +5V through a 10KOhm resistor and pin 22 is connected to a circuit that switches the full high current 5V to pin 25.

I have checked with a multi-meter and pins 21 and 22 are connected to each other and nothing else on the side of the drive.
So, this makes a lot of sense. If a printer is connected to the parallel port then pins 18 to 25 are all ground.
With 0 Volt on pin 21, the 10KOhm resistor is there to limit the current to ground, which is negligible. With 0 Volt on pin 22, transistor Q2 will not conduct and neither will Q1. Pin 25 will be Ground.
With the floppy drive connected, 5V will be present on both pins 21 and 22, leading to proper 5V to supply power to the floppy.
This is also what the manual for the armada is showing.
My drive is identical to the pictures posted by @mtest001 in the other topic.

EduBat wrote on 2025-02-18, 19:21:

Looking at the image I posted earlier and this one we can see that pin 21 is connected to +5V through a 10KOhm resistor and pin […]
Show full quote

Looking at the image I posted earlier and this one we can see that pin 21 is connected to +5V through a 10KOhm resistor and pin 22 is connected to a circuit that switches the full high current 5V to pin 25.

I have checked with a multi-meter and pins 21 and 22 are connected to each other and nothing else on the side of the drive.
So, this makes a lot of sense. If a printer is connected to the parallel port then pins 18 to 25 are all ground.
With 0 Volt on pin 21, the 10KOhm resistor is there to limit the current to ground, which is negligible. With 0 Volt on pin 22, transistor Q2 will not conduct and neither will Q1. Pin 25 will be Ground.
With the floppy drive connected, 5V will be present on both pins 21 and 22, leading to proper 5V to supply power to the floppy.
This is also what the manual for the armada is showing.
My drive is identical to the pictures posted by @mtest001 in the other topic.

Got it! Yes I see now and that makes perfect sense.

If you have a similar drive and a bit of time and a multimeter, maybe you can create a pinout list of what the rest of the pins are doing in relation to the db25 connector. Maybe there is a way to determine if the floppy drive resembles something to a standard floppy pinout?

Hi,

The LPC47N252 Super-IO datasheet has this table.

It should be possible to build an adapter to allow the connection of normal floppy drives to the Compaqs.
I have 2 drives and both work OK, (although one of them has problems ejecting the diskettes...)
Such an adapter could be useful for people who don't have a Compaq floppy drive or only have faulty ones.

EduBat wrote on 2025-02-19, 12:15:

Hi, […]
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Hi,

The LPC47N252 Super-IO datasheet has this table.

It should be possible to build an adapter to allow the connection of normal floppy drives to the Compaqs.
I have 2 drives and both work OK, (although one of them has problems ejecting the diskettes...)
Such an adapter could be useful for people who don't have a Compaq floppy drive or only have faulty ones.

Perfect, this is just what I need. I will put together a schematic and PCB for this pinout. The adapters are pretty simple to build for anyone wanting to test it once its ready.

EduBat wrote on 2025-02-19, 12:15:

Hi, […]
Show full quote

Hi,

The LPC47N252 Super-IO datasheet has this table.

It should be possible to build an adapter to allow the connection of normal floppy drives to the Compaqs.
I have 2 drives and both work OK, (although one of them has problems ejecting the diskettes...)
Such an adapter could be useful for people who don't have a Compaq floppy drive or only have faulty ones.

I just got around to looking at this in detail today and noticed that this pinout matches the current adapter for the PC-9030 with the exception of the power triggering which could be easily added. So I think the current adapter would work fine with an Armada series laptop if the floppy drive is powered by an external source. I will probably create an Armada series revision of the adapter that triggers the 5v and passes it through correctly, but the current adapter could be used for testing as is.