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ps2 to usb - anyone try this? - pic attached

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Tiger-Heli:


--- Quote from: KenToad on April 25, 2005, 10:53:14 am ---Hmm, I'll check it out again.  I tried several times, I believe, probably doesn't depend on computer specs.

--- End quote ---
Try hot-swapping a PS/2 keyboard.  If that works, you should be able to hot-swap the KeyWiz.

--- Quote ---I'm a little bit confused about your post in the other thread.

--- End quote ---
Okay, here's some more details:

I have a normal work PC with a desktop controller with a KeyWiz that I hot-swap on the PS/2 port (with 2600's disclaimer).

Since I need a keyboard on the PC, and didn't want to buy a new USB one, I use my old PS/2 keyboard with the adapter like you mentioned.  The adapter works but does not work well for keyboard use - i.e. if I hold down the Shift button and type, the third letter on will not be shifted, and if I hold down one key, and then press and release a second key, the first key is no longer sent, even though it is still depressed.

I suspect the same thing would happen with the KeyWiz connected to the adapter.  I.e., it should work after a fashion, but won't work well. . .

--- Quote ---Also, do you still sometimes get the stuck key when you hot-swap the KeyWiz?

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Not lately <crosses fingers>.  And it wasn't a stuck key, it was a stuck output - hard to explain, but tapping any key would clear it, and it hasn't happened again, so I think it was just some crossed wiring somewhere, maybe. . .

Tiger-Heli:


--- Quote from: 2600 on April 25, 2005, 11:05:33 am ---Tiger_Heli,
I think this is like one of the only areas where I disagree with you and wish you would put a disclaimer when you say this. 

Being a Hardware guy you can not hot swap a PS/2 connection.  Now hold on before, you say I've done it seventy times and never had a problem, remember there is a difference between saying I've done it seventy times and actually the spec allowing it.  In the olden days, if you hot swapped a PS/2 connection you were likely to blow a fuse and you'd have a dead motherboard.  Recent motherboards are more forgiving, and I've seen it done on many PC's, but electrically it's not "wise" and it's not designed to operate that way.  I always get the users who say I've done it a hundred times before, but it's that one time out of a hundred and it doesn't work that totally stumps them.  Which is why I disagree with you on this one point,  but only because many users may take your words as truth and may not be as savvy which would leads to frustration on their part if not worst, a dead MB.

I'd love to see one of the manufacturers for these boards step up and say something about it, but not sure if they will.  In any case, I bet the response is we've done testing and it's worked for us, but it isn't designed to do this.

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Point taken.  I agree - the spec does not allow you to hot-swap a PS/2 connection.  I have a disclaimer on my keyboard hacks page.  I also have also done it many times.  The risk is usually not a dead motherboard, but rather a dead keyboard fuse on the PS/2 port.

The explantion that I have most often heard is that you are sending +5V and Ground over the connection so you could possibly short the two and blow the MB fuse, but you are also sending +5V and GND over the USB port and it doesn't have this restriction, so I'm not sure what the reasons are. . .

2600:


--- Quote from: Tiger-Heli on April 25, 2005, 11:24:53 am ---
Point taken.  I agree - the spec does not allow you to hot-swap a PS/2 connection.  I have a disclaimer on my keyboard hacks page.  I also have also done it many times.  The risk is usually not a dead motherboard, but rather a dead keyboard fuse on the PS/2 port.

The explantion that I have most often heard is that you are sending +5V and Ground over the connection so you could possibly short the two and blow the MB fuse, but you are also sending +5V and GND over the USB port and it doesn't have this restriction, so I'm not sure what the reasons are. . .

--- End quote ---

Yeah, your right usually it's just a dead port and you do put the disclaimer on your website.  I think there has just been an large amount of posts recently talking about encoders and just happen to notice it, but like I said it's like one out of a large number of things that I disagreed with.  So pretty good odds.  ;)

Here's some information on the why thing, won't get into all the details though just enought to get the point.  For one thing, during the initial connection of hot swapping a device there is a large surge when connecting the device, this can be like 3 times the current draw. The USB spec accounts for the large surge when initialy connecting a device and allow for 3 or more amps for this short surge.  And for some reason a lot of older PS/2 fuses aren't of the resettable type which makes it even more of a problem as it's not designed to source that amount of current for any period of time no matter how small.

Additionaly, the connection itself is designed so that you are attaching the GND and power before attaching other pins. If you look, inside a Male USB connector you will notice that the outside pins are longer then the inside pins.  These are only part of the problems, but you get I think you'll get the point.

Now, ESD and stuff is a whole nother can of worms that I won't get into.

quarterback:


--- Quote from: KenToad on April 25, 2005, 09:22:22 am ---I just checked at my local Radio Shack and they had this adaptor.
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cholin:

Quick question about this adapter.  I was just on a site and I saw one of these things, so I was wonderring if Ultimarc products can use it too?  Since they detect it and all that crap, I was wonderring basically if there's any special wiring in these adapters, because if there isnt and it's just a wire split into 2 connectors, I can use it with a minipac, right?

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