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is mini USB keyboard possible?

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I was looking for a small and light keyboard to use with my small palmtop computer. Regular USB keyboards are very heavy and big to fit in my purse. I found the keyboard in the second hand market for which the pictures are given below. I do not know with which device this item was used. But looking at the keys, I guess it was a databank type or something like a PDA.

Top view:
Imageshack - cimg2036n.jpg

Bottom view:
Imageshack - cimg2037x.jpg

Imageshack - cimg2038i.jpg

PCB full

There are three cables going to a small 3 piece plug, smaller then the regular earphone plug. Same size plug I have seen being used in old Casio databanks for data backup, to connect to old serial rs232 ports of PCs but I do not know if this one is the same usage or not.

VCC: white

My questions:
1) How can I test if this keyboard is in working condition or not?
2) If it is working how can I make sure what kind of signal system it uses?

In order to be any use to me, I need to make this keyboard a ps/2 or USB keyboard. If it can be made to send ps/2 signals, I can buy a ps/2 to USB adaptor and use it. In the end, I will need to have a mini USB plug to use it with my palm top computer.

I do not understand much about electronics, but I am able to do fine soldering work. I happen to own a multimeter but I do not own an oscilloscop. Any help?
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