Naive questions about keyboards and mice

I have recently had trouble with an Rpi4 with RO 5.28 when the mouse froze or keystrokes would not function. I was using a Raspberry Pi wired keyboard and mouse. I am back in business using an old Logitech K260 wireless keyboard and mouse. The episode made me realize how little I understood about how these peripherals functioned and how RISC OS communicates with them. So here is a list of queries.

1. I note that with Unix I can usually disconnect a USB peripheral, then reconnect, and it continues to function. Not so with RISC OS, where all I can do is switch off. Why?

2. Are the functions of keyboard and mouse disjoint? That is, can one continue to function while the other cannot?

3. Do keyboards break? Or is the problem with the software that transmits the keystrokes to the computer? How would I tell which?

Over the years I seem to have accumulated a collection of USB mice:

• Logitech MN-M-UAL 120
• H/P
• Raspberry Pi
• Digitus AGM107E

They all appear to work, which is why I am presuming that the problem was with the Raspberry Pi keyboard.

4. Is that presumption faulty?

I am far from an expert, so…

1, Please be more specific. What sort of device? I have removed and reinserted flash drives without problem, ditto mice (in fact as of circa v5.25 I need to do that to get the mouse working on the Beagle, it is no longer ‘seen’ at boot).
Note that removing and reinserting a device will give it a new USB device number. If the driver you’re using doesn’t notice and tries to use the old info… Think of it like a file handle.

2, Yes. They’re different bits of code in the USB driver and they are often (not always) different physical devices. My Pi0 runs with only a mouse attached (no keyboard) as it usually boots OSMC.

3, Trust me – keyboard membranes are pretty fragile. Flexing, biscuit crumbs, anything even remotely liquid, all can wreak havoc. If the membrane is duff, chuck the keyboard. Trust me here too, I’ve tried to fix several and if you’re lucky enough not to make it worse (too easily done) then any fix will be temporary at best.
To be honest, it doesn’t matter whether it’s the membrane (most likely) or the controller (least likely), if you press X and nothing happens, it’s broken, end of.

3b, Unless you mean RISC OS. With the exception of weird extra keys like Play and Sleep that RISC OS doesn’t support, there’s no reason why some keys might work and others not. Your typical results will be it works, it doesn’t work, it soooort ooooffff woooorrrkkkksss, or the machine stiffs the moment you press a key. It’ll be quite repeatable.

3c. Because the RISC OS USB keyboard code is rather simplistic, you’ll typically find that the fancier a keyboard is the less likely it is to work correctly with RISC OS. My Microsoft touchpad keyboard just about works, but the machine crashes hard the moment I touch the touchpad. I also had a many-key-rollover special gaming keyboard (not my choice!) that either gggaaavvveee too many presses or none at all. But credit to RISC OS, Linux flat out refused to work with it. ;)
Just give the machine whatever you can buy for a tenner at Tesco. It’ll be happy with the most basic keyboard you can find. I know, I’m using one!

4. Just as with everything, not all keyboards are alike. The fancier and weirder it is, the less it is likely to work correctly. The basic HID part of the keyboard is supposed to be standard, but manufacturers love to add stuff, and not always in sensible ways.

4b. If the keyboard works with something else (Windows, say) then it’s just a bit too complex for RISC OS.

When you say Raspberry Pi keyboard, do you mean https://www.raspberrypi.com/products/raspberry-pi-keyboard-and-hub/ ?
Isn’t that basically the same thing as on the Pi400?

What sort of device?

Mouse.

Flexing, biscuit crumbs, anything even remotely liquid, all can wreak havoc.

Yes, I lost a nice compact Maplin keyboard to a mug of coffee a while back.

When you say Raspberry Pi keyboard, do you mean https://www.raspberrypi.com/products/raspberry-pi-keyboard-and-hub/ ?

Yes. Thanks for the feedback.

A couple of other things to check:

1 – Hav eyou got the latest firmware installed on the Pi4.

You can do this via booting up Linux on it and then start a terminal:

sudo rpi-eeprom-update

If it says there is an up to date version then :

sudo rpi-eeprom-update -a

Some older versions had issues, power/USB-reset blips etc AFAIK, and the latest does allow the Pi4 to clock faster as well.

Also pre hardware Rev 1.2 boards had issues with non – official USB-C power supplies.

Also what power supply are you using as some don’t supply the required power or are borderline.

Finally the keyboard looks like the one installed in the Pi400 so perhaps some tweaks to the ROM may help so try the latest 5.29 ROM in the place of 5.28.

Disc updates may also help but backup is your friend :-)