use a PS2 KVM with ADB peripherials?

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dankephoto's picture
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switching the ADB signals over the PS2 circuits in the KVM?

dan k

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dankephoto's picture
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Joined: Dec 20 2003
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use a PS2 KVM with ADB peripherials? (the actual post :)

I've got a couple of modern all-electronic VGA KVMs with PS2 ports. I have no idea what the KVM does with the PS2 signals, but can anyone think of any reason ADB stuff might not work? (provided of course that I wire up adapters that use similar function pins) I imagine the clock and data pins in the KVM simply pass-through their signals, and the KVM doesn't do anything other than switch those ports from one source to another.

Understand, I'm not trying to connect ADB peripherals to PS2 ports, I just want to use the circuits in the KVM to pass through (and switch) the ADB signals. I'm using ADB keyboard(s) and TurboMouse(s MIce?), connected to ADB on my 9600, and to USB on my Quicksilver via an iMate adapter. I'd even like to bring my wintel box into the mix using an iMate.

I bought the KVMs (a 2 port and a 4 port) thinking for some crazy reason they were USB jobbies, but they are PS2 for which I have no use (the PS2 part.)

The video switching works really great, the best KVMs I've ever used. There's no ringing or jitters or artifacts of any kind. I've been using the video switching but I still have to have multiple keyboards, so if I could repurpose the PS2 ports to either ADB

Oh yeah, why bother? Why not just buy an ADB or USB based KVM? Well, ADB KVMs are non-existent and I haven't stumbled across a cheap enough USB KVM. These KVMs cost $20 for the 2 port and $40 for the 4 port (cables included with both), very affordable. And the video switching works so great I'm loath to now go out and buy another KVM.

ADB pinout
1 ADB
2 PSW (Power Switch)
3 +5V
4 GND

PS2 pinout
1 data
2 (reserved)
3 gnd
4 +5v
5 clock
6 (reserved)

(hmmm, maybe even USB . . . ?)
USB pinouts
1 VCC +5 VDC
2 D- Data -
3 D+ Data +
4 GND Ground

dan k

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dankephoto's picture
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Joined: Dec 20 2003
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more stupid (and probably useless) synformation

This is a big waste of time (I suspect) as PS2 isn't a two-way bus IIRC, where ADB of course is.

The KVMs uses a Philips 74HC253 to multiplex the KB/mouse signals to the 'puter ports. Then 74hc4052 chips service the actual connections to each 'puter.

If anyone has a clue about these sorts of chips, can they handle back and forth traffic like ADB or are they only able to move data from the peripherals to the computer? It sucks to have these notions and then have no clue 'bout the basics needed for real understanding. Aye caramba!:?

Oh, of course I could just wire up an ADB device to the KVM and thence to a Mac, but I'm too much of a . . . errr, another word for a cat.

TIA,

dan k

74HC253 features:
· Non-inverting data path
· 3-state outputs for bus interface
· and multiplex expansion
· Common select inputs
· Separate output enable inputs
· Output capability: bus driver

The 74HC/HCT253 have two identical 4-input multiplexers with 3-state outputs which select two bits from four sources selected by common data select inputs (S0 ,S1 ). When the individual output enable (1OE, 2OE) inputs of the 4-input multiplexers are HIGH, the outputs are forced to the high impedance OFF-state. The “253

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jt
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Joined: Dec 20 2003
Posts: 447
Duck soup . . .

. . . sounds like standard gate arrays with the "multiplexer" ICs used to decode the switches on the front panel/enable the gate ICs.

Then again, I'm REALLY tired ATM . . . :Smile . . . wire it up and test the two port KVM on a cheapsh . . . . . . erm . . . :? . . . dumpster ballast Mac.

jt Wink

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