Abstract: Memory blocks in an integrated circuit (IC) chip can be repaired by employing automated test equipment external to the IC chip to aid in burning fuses on the IC chip by encoding the fuses with binary-encoded numbers. Each binary-encoded number represents a bit position of each “1” bit of a repair control word corresponding to a defective memory location. During a repair sequence preceding operation of the IC chip, the binary-encoded numbers are read out of the fuses and used to form a serial stream of repair chain information.

Abstract: Memory blocks in an integrated circuit (IC) chip can be repaired by employing automated test equipment external to the IC chip to aid in burning fuses on the IC chip by encoding the fuses with binary-encoded numbers. Each binary-encoded number represents a bit position of each “1” bit of a repair control word corresponding to a defective memory location. During a repair sequence preceding operation of the IC chip, the binary-encoded numbers are read out of the fuses and used to form a serial stream of repair chain information.

Abstract: The control software and hardware in the tape drive control unit creates and manages a header segment at the beginning of the magnetic tape. This header is interposed between a leader portion of the magnetic tape on the 3480-type cartridge and the remainder of the magnetic tape contained therein. This header segment contains two sections, a first of which is a data record directory that is used by the control unit to denote the location of each data record written on to the magnetic tape as well as administrative information associated with the data record. The second section of the header is an administrative information section that contains data relating to the magnetic tape itself.

Abstract: The control software and hardware in the tape drive control unit creates and manages a multiple level error detection and correction system to protect the data written on the magnetic tape. The helical scan data write circuits operate on the received stream of data records to produce two orthogonal error detection and correction codes on a scan group level. The data write circuit divides the received stream of data records into data segments, each of which contains a predetermined number of data bytes. A first of these scan group error codes is generated on a per data segment basis while a second scan group error is generated across multiple data segments. A third level error correction code is also used to protect an entire scan group rather than data on a per byte basis. The third level error correction code generator produces an error code over a predetermined number of sequentially written scan groups to enable the control unit to reconstruct an entire scan group if its data integrity is compromised.

Abstract: Control software and hardware in the tape drive control unit creates and manages a header segment at the beginning of the magnetic tape. This header segment includes an administrative information section that contains data relating to the magnetic tape itself. The administrative information includes read/write status information such as the write protect status of the magnetic tape that enables the tape drive control unit to manage the data records written onto the magnetic tape without reference to any other source of administrative data. In addition, each data record written on the magnetic tape includes a header which denotes the read/write status of the data record.

Abstract: The control software and hardware in the tape drive control unit creates and manages a header segment at the beginning of the magnetic tape. This header is interposed between a leader portion of the magnetic tape on the 3480-type cartridge and the remainder of the magnetic tape contained therein. This header segment contains two sections, a first of which is a data record directory that is used by the control unit to denote the location of each data record written on to the magnetic tape as well as administrative information associated with the data record. The second section of the header is an administrative information section that contains data relating to the magnetic tape itself. The stream of data records is divided into data segments, a plurality of which comprise a single helical scan track. The helical scan tracks are formed into scan groups and written on the magnetic tape.

Abstract: This system makes use of a tape cassette helical scan tape transport and a modified 3480-type magnetic tape cartridge as the data storage media. The merging of these two incompatible elements is accomplished by the use of a novel interface that implements a "virtual tape cassette" by providing a takeup reel positioned with the magnetic tape cartridge in a relationship that substantially matches the format of a magnetic tape cassette. A short tape threading arm is used to retrieve the leader block from the tape cartridge and thread the magnetic tape over a short tape threading path to the takeup reel. Once the tape is affixed to the takeup reel, the helical scan tape loading mechanism transports the length of tape that is now exposed between the tape cartridge and the takeup reel to the rotary heads. The helical scan magnetic tape cartridge has the same exterior dimensions as a conventional 3480-type magnetic tape cartridge but is implemented in the inverse configuration.

Abstract: Method and apparatus for temporarily storing multiple data records in a data processing system which includes a host computer, a cache buffer subsystem, and a magnetic tape drive subsystem. A microprocessor, acting in part as a cache manager, directs the transfer of data into and out of a memory in the cache buffer subsystem by setting up a fill address register, a drain address register, and a start of record address register. Through utilization of a CRC byte to detect errors without correction, and a stop bit to locate the end of a record, values of the registers are compared dependent upon whether there is data being filled or drained to properly manage the temporary storage of data within the memory.

Abstract: A data clocking and detection system for a digital data storage system includes a common controlled oscillator for the multiple tracks. A phase detector for each track includes a counter and decoding circuitry producing outputs representing the time occurrence of transitions in the data with respect to bit cells defined by multiple clock pulses for each bit cell. Phase errors are used to control the frequency of the VCO, and large phase errors are used to add or subtract a count from the phase counter in each phase detector.