1) Pre 99 In 99 there were multiple fields of play.

2) In 1999 the last year the pre-IFI controllers were used, the silver box between the OI and the small antenna was a wireless modem (also called a wireless RS 232? interface). The black boxes now used are probably almost the same thing in a slicker package. Actually if you cruise the net you can get the schematic of the pre-IFI controller with a parts list. (Probably easier /cheaper/better to buy an edubot!)

3) before my time......