View Full Version : Standard diskette drive adapter for Personal System/2 edgecard chassis

August 14th, 2017, 01:56 AM
Would anyone be interested in buying one? I'm aiming for the cheapest production possible while not making this board a mess, given that the design is extremely simple. Not sure what to do with the "drive type" pin yet, given that it does not simply do well apparently with other machines when pulled high or low, so I fear that a simple jumper toggle might not be possible.

EDIT: I've made the first complete draft of the design, which I have done completely over from scratch based on hours of measuring the only board I have matching such design. The initial drawings were basically your average 5 minute guesswork. :sigh: Hopefully, this should be transferable to something that KiCad or Eagle can actually draw now. I have no idea if the edge card connector was designed for 1mm thick boards; the board I have with me right now seems a bit smaller. Not so sure on the sides of the connector, too. On the top surface of the connector, the sides looked thicker to me than between the gold plated pins, so I assumed the same here.

vBulletin is crap at handling small images, so I'm going to directly link this:


What I liked about doing this is that I've trimmed the draft down to even a size smaller than that of my original adapter board that I based these designs off of. The metal pins might be too far from each other though, given that a 16 pixels per 5 millimeters scale isn't exactly precise compared to real life measurements and given the calculations, the pitch per pin might be a few digits off.

August 14th, 2017, 01:52 PM
It looks promising, but I think there are a few problems with trying to sell something like that. First that's for the 40-pin interfaces found in the early PS/2's, later ones used a 34-pin interface. So It limits it's market, that's already in a small market. Second in the model 50 (and 70 I believe) there are very tight constraints on space IIRC. So in its present rough draft state, I don't think it would fit.

It would be interesting, but I worry if you got 50 made, you'd have 40 left 10 years later. It's very interesting, Let me know if you want me to crack open my model 50 to look as space requirements. I will help if I can.

How cheap is cheap? $1, $10, $50?

August 14th, 2017, 10:57 PM
I've done the first complete draft to where it's even smaller than the converter board I used to make the measurements for it! Looking at it now compared to the original drawing, it's a million times better. To save tracing space for cost reasons, I flipped the 34-pin header around vertically so that it can still be inserted in correctly, while the solder points can be mapped straight forward. This way, I don't have to do a whole lot of work, and there's no dead ends for me to escape from.

mR_Slug: I plan to make a few, to avoid having too much with so many left over. About space requirements, as long as there is enough space for the two ribbon cable to fit between the card and the drive, there should be no problems, but yes, I will need help as much as I can. I plan to go low on the price as much as possible as long as everyone is happy, and if things go well, I can get a fellow named waltje to produce a prototype board.

EDIT: Gave a some space between the resistors to avoid sandwiching and conflict.

August 15th, 2017, 12:27 PM
Note: this design is assuming you ARE using the standardized floppy drive cables that have the famous twist in them.

August 15th, 2017, 11:47 PM
In the process of making FreePCB schematics. Ground routing instead of planes is because I am a cheap klutz. Easier than KiCad as far as I know, and I grasped onto it in less than a day. So far, you can call it basically finished, as everything is in place except for the pin 4 functionality... Compared to the first complete draft, I've shifted the resistors around and remeasured the edge connector so that it's very precise enough; unsurprisingly, edge pins are of standard 2.54mm pitch and 1.27mm width.

DRC errors are due to the connectors being nearly close to the board outline, although I don't think this case will bother some fabrication houses as much.

August 16th, 2017, 11:56 PM
Newer design with switch to smaller 7mm body resistors, rendering correctly with OSH Park website. If things go out as planned, I will release the Gerber files and FreePCB design, and perhaps on the way to making the final design, add an option to regulate 5V with 100nF and 47uF capacitors. Ordering this board will require a few more weeks because it needs to be precisely manufactured with a 0.8mm thickness, something that OSH Park's website can do but with time, unless I can find a faster way with a different service.