Keyboard error sound in Windows 10 when stimulating invalid matrix pos

THX1138b

05 Oct 2017, 20:50

I wanted to add some keys to my PS/2 keyboard. The controller has eight rows and 16 columns but the keyboard has 102 or 103 buttons (not sure) so that leaves 20-something matrix positions unaccounted for. I used a breadboard jumper wire to connect the rows and columns in sequence and found five usable vacant matrix positions. I also found a lot of whatever this is; some kind of error? It's what I came to ask about. Does anyone recognise this sound? When I make a quick contact with the jumper wire, I get two beeps but if I hold it down for longer, I can get a bunch of beeps. The sound comes from my proper speakers, not the motherboard piezo thing. Please disregard the image in the below video; it's just what happened to be on my screen when recording the sound. Is the keyboard in distress when I do this or what? Does any other situation cause this sound?

I'm using Windows 10.
Edit: why isn't the YouTube embed working? Here's a link instead: https://youtu.be/zvTZgzK3jTE
Last edited by THX1138b on 06 Oct 2017, 20:26, edited 2 times in total.

User avatar
Daniel Beardsmore

05 Oct 2017, 21:38

To embed, you only use the video ID inside the tags(here, zvTZgzK3jTE). The forum software could definitely be more intelligent about it.

What you need is Switch Hitter — this will indicate what the keyboard is doing.

THX1138b

06 Oct 2017, 20:28

Thanks. I was using a different (and way more basic) scancode capture software but neither software reports anything for the particular matrix positions which generate this error or sound.

User avatar
Daniel Beardsmore

06 Oct 2017, 21:12

I guess there's also the possibility that those matrix positions are undefined and the keyboard is emitting nonsense.

USB HID is weird: a faulty mouse can emulate a keyboard and presumably vice versa. Who knows what your keyboard is doing if it's being given undefined requests.

THX1138b

06 Oct 2017, 21:32

In my case it's a PS/2 keyboard. I'll try it on an older machine I have running Linux and see how that responds. I'm just curious about that nonsense that the keyboard is emitting!

User avatar
Daniel Beardsmore

06 Oct 2017, 21:39

oh yeah, so you said ... I'll use the excuse that it's Friday :P

Post Reply

Return to “Keyboards”