Diagnostic Technique for Use in Disk Drive Controllers
Original Publication Date: 1985-Jul-01
Included in the Prior Art Database: 2005-Feb-18
Two diagnostic techniques are disclosed: 1) checking Cyclic Redundancy Check (CRC) detection circuitry and 2) checking the missing address mark detection circuitry. The CRC detection circuitry is tested by forcing a data read error. The missing address mark detection circuitry is tested by moving the recording head to a location on the diskette medium where no data is recorded. A CRC character is generated and placed on diskette during data write operations and checked during read operations. When data is read incorrectly, the read-generated CRC does not match the CRC character read from the diskette medium, and a CRC error is reported. A control register is employed to change data clocking frequency of the diskette drive unit under control of a microprocessor. The flowchart shows programming flow of the test.