INT 7A - IBMInternational Busiuness MachinesInternational Busiuness Machines) A hardware, software and other service technology company founded in 1911. Personal Communications/3270 - INSTALLATION CHECK AX = FDCBh Return: DX:AX -> PCS/3270 signature block if loaded (see #03839) Format of Personal Communications/3270 signature block: Offset Size Description (Table 03839) 04h WORD PCS/3270 signature (5741h) 06h WORD version (0501h = PCS/3270 v1.0)