Converting an IBM Pingmaster

[cloudhax]

with some research you can also figure out which keyboard are which by looking at minor differences in the keycaps.

I'd love to know more on how to spot which TI-99/4a have the pingmaster compatible keycaps. are they all black? I see some beige models with keycaps that look like they might work

[consideringquiet]

Does anyone have a comprehensive guide to convert this thing?