commands list for SD-CARD:
READ, WRITE, DIR, TIME, LOAD, RUN, CD,
TYPE, DUMP, ASAVE, BAS, DEL, LS, SAVE,
MKDIR, RMDIR, RM, MD, RD, PWD, TEST, 
ADDRESS, HELP, ?, MOUNT, EXIT.

commands list for IEC:
@DEV, @DIR, @L, @R, @S, @BL, @BR, @BS,
@ERR, @CMD

USE HELP COMMAND FOR MORE DETAILS

