Re: PS-2 Keyboard for Aplle II ?

In <43b5fa3c$0$95958$742ec2ed@xxxxxxxxxxxxxx> Don Bruder wrote:
> In article <1135995653.165903.15480@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
> "Gabriel" <usenet@xxxxxxxxx> wrote:
>
>> I'd drop PS/2 and go for trying USB. Why replace one aging interface
>> wth another?
>>
>
> Primary difference between USB and ps/2, elcetrically speaking: The
> end of the cable.
>
> I've meter-verified that the USB-->ps/2 converter that came in the
> package with my USB mouse simply "rearranges" the USB pins to fit the
> ps/2 plug - Which seems to be further confirmed by the fact that
> putting the converter on the end of the mouse cable and plugging it
> into an actual IBM ps/2 system is an "it just works" thing. Plugging
> it into a USB port without the converter is the same - "it just
> works". Ditto when I put the converter on the end of my USB keyboard
> cable and jack it into the ps/2, or swap it to my USB-equipped Mac
> without the converter - Just like the rodent, either way, "it just
> works".

USB and PS/2 are completely different, elctrically speaking. PS/2 is
actually quite a simple protocol, especially since IBM restricted it to
only allow one device per port, unlike ADB where you can have multiple
device. The PS/2 protocol can be handled by the smallest, cheapest
microcontrollers available, but USB requires a mid-range micro with
special USB hardware.

The PS/2 to USB (or USB to PS/2) adaptor plugs that come bundled with
mice are simply plug converters, and they won't work with just any mouse.
The mouse itself has to be programmed to work with both PS/2 and USB
protocols. Presumably when the mouse first powers up it determines which
protocol it should use based on what sort of data or clock signals it
sees.

--
Roger Johnstone, Invercargill, New Zealand
http://roger.geek.nz/
________________________________________________________________________
No Silicon Heaven? Preposterous! Where would all the calculators go?

Kryten, from the Red Dwarf episode "The Last Day"
.

Relevant Pages

  • Re: PS2 to USB converter
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  • Re: Installing 5.3 without a PS/2 keyboard
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    (comp.unix.bsd.freebsd.misc)
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  • Re: Adding/removing mice dynamically
    ... > I'm having the following problems with my Thinkpad laptop running Debian ... the Trackpoint and the PS/2 mouse port share data lines. ... I think you'll have to set the protocol to PS/2, ... or buy yourself a USB mouse. ...
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  • Re: How to update hardware detection and configuration?
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