OT, Bill Gates: Ctrl + Alt + Delete 'was a mistake'

[The Daring Dufas]

I actually think it's a good idea because it prevents a lot of "mistakes". ^_^

TDD

[Tomsic]

Ctrl+ALT+Delete is also good for quickly shutting off non-essential processes which suck up resources, such as RAM when you want to do heavy work. Microsoft Security Essentials is my usual turn-off candidate since it starts automatically again after a while.

Tomsic

[Frank]

I have to use it to log into clients computer to put in PW using XP. Win8 does not have it and clicking any single key brings up PW request.

[gfretwell]

It says a lot about the stability of his products when he says he wanted a one button reboot.

IBM wanted to make it an unlikely accidental key stroke. It came from an IBM engineer designing the hardware long before Bill Gates was involved.

You can remap a single keystroke to that code or even send it from the software.

[krw]

I don't believe that's true. At least as I recall the original schematics, a C-A-D creates an NMI which can't be done with a single keystroke without redesigning the keyboard. With a USB keyboard, you're probably right. There is no interrupt in the USB cable.

[The Daring Dufas]

I don't think it should be too easy to delete something. I service a lot of computer systems in retail stores and many of the users are extremely goofy and I know they hit the wrong key 1 out of 3 keystrokes. I can really imagine the horror show I would have to contend with if those goofy people had a single key to kill a program. o_O

TDD

[gfretwell]

I know you can do it with a tiny COM program and you can set up a PROMPT command from ANSI.SYS to call that program. I used to call a soft boot in programs I wrote sometimes. Whether you can actually put in the CAD key code in a prompt, I am not sure. I suppose I could dig through my tech ref book and see.

[krw]

I'd like to see how that works on an original PC. The NMI is a hardware interrupt.

You can branch to the boot location, I suppose.

[gfretwell]

It comes from the BIOS, not the keyboard. There is nothing in a keyboard cable but clock, data 5v and ground.

It is a function call.

[krw]

Not true. The original PC keyboard had an interrupt that tickled the NMI directly. That was the whole purpose behind the C-A-D, to make sure you didn't reboot accidentally. Nothing else was going to stop it.

[gfretwell]

It is still just clock, data +5v and ground. Where is this interrupt coming from if it is not just a command?

[krw]

WRONG!!!! (good Lord, READ!)

Pin-3 on the AT keyboard connector was the interrupt. It was deprecated at some point but it *was* in the original PC.

[gfretwell]

Not true at all. I have the tech ref and I can scan that page if you like. Pin 3 says "keyboard reset, not used by keyboard" That is from the 5150 (original PC) book

1 is clock 2 is data 4 is ground 5 is +5v

Pin 3 may have been used in the 5100 (in the 70s) but we didn't sell enough of those for me to ever see one.