INT 2F - TBSCANX - INSTALLATION CHECK
AX = CA00h
BX = 5442h ('TB')
Return: AL = state
00h not installed
BX = 7462h ('tb') if BX was 5442h on entry
Program: TBSCANX is a resident virus scanning module by Frans Veldman.
Notes: programs may perform virus checks on themselves, other program files,
or their data files by invoking the TBSCANX API.
current versions of TBScanX don't actually check the value of BX