I ran into this problem with my original Model M. All the PS/2 to USB converters I bought (even the blue square one quoted in the article as working) were borderline and they would sooner or later lock up and require a reboot (you really shouldn't hot-plug a PS/2 keyboard, as some machines have a fuse soldered on their board).
I have not tried any of the new keyboards sold by Unicomp (I had one in the past), but I see their newest version of the Model M has a USB interface and presumably it's reliable.
That's a worst-case of 148mA, which even allowing for an extreme additional 100mA drawn by the converter is still well below the 500mA a USB port should be able to supply. I suspect the problem is actually signal integrity, and the fact that modifying the board to add stronger pullups works is more evidence in this direction.
And it won't affect MCU power draw at all as PS/2 is open collector - the MCU is never driving the data or clock high at all.
The best converters don’t lock up but still hard reset “under duress” when typing away. (The only good converter I found was by Tripp Lite.)
Ah that's weird: years ago I bought two of these "cube" adapters and used them for years and never had any issue. But then I also switched to Topre switches (HHKB Pro JP keyboard).
Isn't one the selling point of these adapters anyway that it's USB, hence you can hotplug the keyboard should it lock up (which never happened to me but when you use one, it's USB plugged into the mobo, not PS2).
They are manufactured by the same company that made the original for IBM (in Tennessee, USA).
I was worried as many reviewers claimed they were slightly worse than real Model Ms but I have to say, I think they got everything down. (I've used an SSK and Lexmark Model M for reference.)
I own one and I love it.
If you want this experience, I’d suggest you grab a used model M on eBay. TFI had good reference on usb to ps2 adapters that work. For an xt cable, you can buy a sorros (sp?) converter for 40 bucks. Or a new usb to RJ cable that will plug directly into the keyboard.
Electrically, not perfect (but I don't know what the old ones were like). I have a USB one that simply died when I lost power one day. I was astounded to find that it was the keyboard that actually died and not the USB port stopped working or something.
The most reliable keyboards I've found to actually be basic Keytronic models.
I bought an endura pro, the ultra-nav (the red nub in the middle of the keyboard) doesn't work properly: it moves at different speeds depending on whether you're moving towards the right vs left. It drives me crazy.
The problem seems to be that it gets stopped by a key and doesn't get tilted enought to trigger pointer acceleration.
I'm supposed to erode a key somehow... To allow the lever to move a bit more, but it's a dumb solution to a problem that shouldn't be there in the first place.
I used to think the Model M was great. And then I bought a reproduction Model F and now I'm convinced the Model M's belong in the dumpster. Okay, maybe not, but they're definitely inferior. The F has a lower actuation force, which is nice for people like me who mash on the keyboard like monkeys. It also feels 'smoother'. The inner assembly is individual barrels instead of a single plastic barrel sheet, so repairing individual keys is a lot easier. Also it's held together internally with clips instead of blobs of melted plastic rivets, making it possible to actually get inside to replace flippers or barrels without going through an entire ordeal of 'bolt modding'. It's just a much higher quality overall.
If anybody is interested in a brand new (reproduction) Model F, they're still being sold: https://www.modelfkeyboards.com/
The reproductions are nice because they have a semi-modern layout (compared to the original Model F's that are generally available on eBay) and fully programmable controller, so you can give it whatever layout you want. It can also be physically configured to resemble the HHKB if you're into that sort of thing.
but I find the ortholinear or column-staggered layouts of keys to be a big improvement over the asymmetric row-stagger of standard keyboard layouts.
From the IBM PC/AT schematics we can find that the pullups are on the host side and are 10k, and the Intel 8042 used as the interface controller has a Vih(min) of 2.0V. On newer motherboards, the KBC is usually built into the SuperI/O. As an example, I picked the D845GRG as one listed motherboard that required the modification, and discovered that it has either an SMSC LPC47M172 or NS PC87372. They both specify a Vih(min) of 2.0V, but the datasheet for the former surprisingly recommends a 2.7k(!) pullup for the PS/2 ports. That is surprising because the original IBM PC/AT only needs 10k. Maybe these "non-compliant" motherboards are running the port at a faster clock than the original?
From my limited electronics experiencence, you need a pull-up resistors when connecting TTL ICs to CMOS ICs.
https://github.com/mschwingen/hardware/tree/master/modelm-us...
https://blog.lmorchard.com/2016/02/21/modelm-controller/
https://www.crackedthecode.co/how-to-supercharge-your-ibm-mo...
https://hackaday.com/2018/11/30/new-part-day-the-twenty-five...
Looks like someone already made (at least the source) for an adapter based around that MCU family available:
https://github.com/zhuhuijia0001/ch559-usb-host
As for relative lack of availability, I think that says more about how many people want to use an old keyboard with a new computer (semi-common) vs. a new keyboard with an old computer (rare).
The adapter I bought was complete junk and didn't seem to work correctly, but I had some Pro Micros lying around (about $5 a piece) and managed to flash them with the Soarer's Converter firmware. Then I cut the 2 PS/2 connectors off of the cheap adapter and soldered them to the correct pins on the Pro Micros, and I ended up with 2 converter cables that worked just fine.
If you want cables that don't look like you built them, you can find Soarer's Converter cables on eBay that look professionally made.
This article is 16 years old?
Without any technical knowledge (not at the level of the author of the article) and in my little experience, I can confirm the issue about the long cable not working and the short one working, it happened to me a few times, but in my ignorance, I thought only "ha! the cable is too long and there must be some voltage drops/internal resistance issue", never thought of the possibility of adding resistors (that does sound counter-intuitive, at least to me).
No flashy leds just a very good keyboard!
