Abstract: A programmable menu driven qualifier designed to make the abstract nature of small computer system interface (SCSI) definition easier to understand and work with. The qualifier is intended for testing and evaluating direct access and sequential access SCSI devices, such as disc drives and tape drives connected to the qualifier by an SCSI bus, the testing being carried out in accordance with ANSI SCSI-1 and ANSI SCSI-2 definitions. The qualifier is completely menu driven, and all commands are executed with a single keystroke of the keyboard. The qualifier uses a simple built-in concept which allows an operator quickly to become familiar with an SCSI protocol and command structure.