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New Product: KeyWiz-QD™ - GroovyGameGear
diverdown:
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I'm looking into some sort of wiring product to go along with this. Not sure what form it's going to take at the moment though.
RandyT
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Just 1 word
Bloody Fantastic
Tiger-Heli:
To clarify, I have had problems hot-swapping PS/2 mice, not keyboards.
Guaranos:
--- Quote from: Havok on May 22, 2007, 02:39:22 pm ---Yeah - I've seen computers lock up when "hot-swapping" a ps/2 port. Does stop me from still doing it on work computers - usually it's fine...
--- End quote ---
In some cases it can do worse than cause a lock up. It's rare, but it can cause you to short out your keyboard or mouse port. I've only seen that once or twice in many years working with PC hardware.
As for the DB-25 M/F cables, I just threw out a big stack of them a couple of weeks ago (along with M/M and F/F cables) since I no longer own any devices that use them. Now that I think of it, my computer that I use daily doesn't even have a parallel port on it...
RandyT:
--- Quote from: Guaranos on May 23, 2007, 07:39:46 am ---In some cases it can do worse than cause a lock up. It's rare, but it can cause you to short out your keyboard or mouse port. I've only seen that once or twice in many years working with PC hardware.
--- End quote ---
I've never seen one "lock up" when the keyboard is swapped out, but anything is possible I suppose. Hot swapping the PS/2 mouse port can be more troublesome.
Also, the port does not "short out". In the old days, keyboards were big, and power hungry. Lots of discrete hardware, mechanical switches and so on. The port wasn't originally designed for hot swapping, so on very old motherboards (we're talking 486 / Pentium 1 era and before) they had only a small fuse to protect the rest of the system from a short circuit in the keyboard. The ancient keyboards also had nothing that would ramp the power to prevent a surge from popping the fuse, and that is what caused the problem. BTW, those old motherboards weren't dead, they just didn't have 5v going to the PS/2 port anymore. A quick splice of the 5v supply into a short PS/2 extension cable and you were back in business.
Fast forward to today. The power and data lines on modern motherboards often go to the very same places as those connected to the USB ports. Quite a while back, more devices started using the PS/2 port for an external power tap, so more robust power handling was built into the circuitry. Self resetting breakers have become inexpensive and have pretty much taken the place of the fuses. Modern keyboards (and the KeyWiz) draw very little power compared to the old beasties, and have components to rapidly ramp up the power rather than creating surges when they are plugged into the ports.
We have sold thousands of PS/2 Keywiz's and to date have had zero reports of someone damaging their system through a hot-swap. I'm not saying it can't happen, but the numbers indicate that you might have a better chance of being struck by lightning :)
RandyT
Guaranos:
--- Quote from: RandyT on May 24, 2007, 11:31:17 am ---Also, the port does not "short out". In the old days, keyboards were big, and power hungry. Lots of discrete hardware, mechanical switches and so on. The port wasn't originally designed for hot swapping, so on very old motherboards (we're talking 486 / Pentium 1 era and before) they had only a small fuse to protect the rest of the system from a short circuit in the keyboard. The ancient keyboards also had nothing that would ramp the power to prevent a surge from popping the fuse, and that is what caused the problem. BTW, those old motherboards weren't dead, they just didn't have 5v going to the PS/2 port anymore. A quick splice of the 5v supply into a short PS/2 extension cable and you were back in business.
--- End quote ---
I know that it was usually the fuse popping, and not technically the port shorting out, but you can also fry the microcontroller that controls the port itself. I was avoiding making the distinction to save some people's eyes from glazing over, since most people, even some in a technically proficient group like this one, will probably just consider the port "dead."
From the wikipedia article on PS/2 connectors:
"PS/2 ports are designed to connect the digital I/O lines of the microcontroller in the external device directly to the digital lines of the microcontroller on the motherboard. They are not designed to be hot swappable. Hot swapping PS/2 devices usually does not cause damage due to the fact that more modern microcontrollers tend to have more robust I/O lines built into them which are harder to damage; however, hot swapping can still potentially cause damage. Shorting one pin to another on a PS/2 port can easily kill one or both microcontrollers."
The full article: http://en.wikipedia.org/wiki/PS/2_connector
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