For new style RadioTrack cards only.
This function checks if the new-style RadioTrack card is present in the system at the particular I/O location. It is not a fool-proof way of detecting the radio card, but in most cases it will work. The format of the function is:
return_data = RT2Present( rt_address )
The rt_address is the decimal value of the card's I/O location 780 (30C hex) or 524 (20C hex).
return_data returns the following values:
0 Not present.
1 Present.
10 TESTCFG.SYS could not be opened.
27 Error reading radio card.