Commodore 64 Koala as an XY Pad?

[unrise_lyrical]

...I'm sure it would be way too hard, but I thought it was worth asking about anyway. Don't know how rare they are, but I've seen one or two Commodore 64 Koalas around over the years. For those that dont know what they are:

from what I can see its basically just a very early form of graphics tablet. It's touchpad size is almost the same as a Kaoss pad....

how difficult would it be to turn one of those into an XY midi pad? It is already designed to take physical data then send it into a commodore 64s joystick socket...could this be somehow changed into midi CC information? more or less how the touchpads on novation SLs work...

Just a thought :)

Andrew

[cimo]

hi

if you are using a computer there are already pad to midi converter, if you are not then i would go for the spectrasymbol touchpads although afaik nobody s came out with code for them

Simone

[unrise_lyrical]

Hi Simo, im sorry, I dont think I full understand what you mean? Do you mean if I run that directly into a computer, there is software already written to interpret the signal and change it to MIDI?

[Narwhal]

I had one of those Koala pads exactly like that way back in my Apple ][ days!  Just note: you had to use the "pen" with it because it wouldn't detect a fingers pressure.. though you could use your fingernail I remember it hurt.  It liked a fair amount of pressure to detect position.

[stryd_one]

Uhm I think these fall into the "super rare" category heh... never seen one before :)

Really wanna know if you can mod it? Crack it open and show us it's insides....

[nILS]

And by "crack open" he means "carefully open it trying really, really hard not to break it"

[Narwhal]

The Koala pad for the Apple ][ should be very easy to hack even without opening it.  Perhaps equally so for the C64 version, but I'll speak about what I know.  Years ago I remember opening my Koala pad (I believe screws were under the rubber feet and very easy to open) that I owned just around the time that I was first getting interested in electronics.  I remember that the pad component itself was separate from a very small circuit board that had few chips on it (I think 1 or 2 at most). 

It seems to me this could be hacked from two directions:

1) open the pad and draw a circuit diagram and look up the data sheets on the chips inside.

2) Study the Apple joystick interface.  Apple ]['s were extremely open devices long before anyone started touting open standards!  I still have the original Apple motherboard circuit diagram that came attached in the back of one of the manuals.  The process for reading the joystick was very well documented back in the day and often included descriptions of how the joystick circuit itself worked.  I know the Apple ][ joystick port was a standard 16 pin dual inline socket on the motherboard and I believe that the axis values were measured using circuits that measure that charging times of capacitors as altered by the axis potentiometers.  I'm certain I could scan you the joystick port (if the net doesn't already have this available) from the schematics and you'd then have the pinout and know where to apply 5V to make the pad give you a resistance.

[unrise_lyrical]

Uhm I think these fall into the "super rare" category heh... never seen one before :)

Really wanna know if you can mod it? Crack it open and show us it's insides....

not exactly :) there are 2 for sale on ebay at the moment, one in OZ.

Id buy it and open it up...but if it takes a fair amount of force to use then it probably isnt worth spending the cash on..as it wont be overly useable for actual performing :(

[SuburbanBoy]

if they work like paddles, it's probably 470Ohm.