Re: IIGS ADB mouse - Can it be adapted to IIe/IIc use??

[et472@FreeNet.Carleton.CA (Michael Black)]

Roger Johnstone (rojaws@ihug.co.nz) writes:
> In <bklpq4$57r$1@freenet9.carleton.ca> Michael Black wrote:
> 
>> Given that I thought the mouses for the earlier Apples were on the 
>> level of the original Mac mouse, no.  ADB, like serial and PS2 mouses 
>> for the IBM world, send out serial data.  The earlier computers are 
>> looking for a a number of discret lines, carrying such things as up/
>> down, left/right, and their 90 degree shifted complements, and button(
>> s) press.  The only way you could get a useful mouse out of an ADB 
>> mouse connector would be to throw in a computer to do the conversion.
>> 
>> But, if you really want to mess the ADB mouse, likely you can find
>> the needed signals inside the mouse.  You'd bypass the IC in there,
>> and bring out the signals directly from the button swith, and the 
>> outpus of the 4 optocouplers, plus feed some voltage in to power the 
>> optocouplers. I once did this with an IBM type serial mouse, bringing 
>> out those signals to make a spare mouse for my Mac Plus.
>>
>> In other words, the ADB mouse is a superset of what's in a non-ADB 
>> mouse, and if you are willing to modify it, likely you will get a 
>> working mouse.
>>
>>   Michael
> 
> The old Apple mice also have a buffer or voltage comparater chip inside 
> them, but I think that's just so the optoswitches produce a nice square 
> output, perhaps for hysteresis too.
> 
Yes, they use an LM339 quad comparator.  If someone wanted to get fancy,
they could stuff something like that inside the mouse.

When I converted that IBM type mouse, it was more out of curiosity.
I didn't like it as much as the Mac Plus mouse, so I never used it
very long.  However, it did seem to work fine with the optocouplers
feeding the Mac directly.

  Michael