Symbol Device IOCB
C: Cassette tape unit #7
D1:-D9: Disk units 1-9 (number available depends on DOS)
E: Screen editor #0
K: Keyboard
P: (P1:) Printer
P2:-P8: Alternate printer; e.g. most parallel are P2:
R1:-R4: RS-232 interfaces; requires handler to be loaded
S: Screen #6
Z: R-Time-8 Clock; requires handler to be loaded