Abstract: A hardware assisted memory module (HAMM) is coupled to a conventional computer system. During normal operation of the computer system, the HAMM behaves like a conventional memory module. The HAMM, however, detects and responds to at least one of the following trigger events: 1) power failure, 2) operating system hang-up, or 3) unexpected system reset. Upon detection of a trigger event, the HAMM electronically isolates itself from the host computer system before copying digital information from volatile memory to nonvolatile memory. Once isolated, the HAMM takes its power from an auxiliary power supply. The HAMM can be configured to copy all or part of the digital information to nonvolatile memory. Upon either a request or at power-up, the HAMM copies the digital information from the nonvolatile memory into the volatile memory. If there is a normal computer shutdown, the operating system will first warn the HAMM before shutting down, thus precluding it from performing a backup operation.

Abstract: A hard disk format is disclosed which sequentially arranges a number of different sector types, each having a different format, into frames which are repeated around the tracks of a magnetic disk. The sector types and frame arrangements are chosen so that servo bursts are optimally located around the tracks of a magnetic disk. The sectors of the magnetic disk may have servo bursts located virtually anywhere within each sector. A magnetic disk controller used in conjunction with the magnetic disk processes each sector during reading from or writing to a sector according to whether or not the sector contains a servo burst.

Abstract: A novel disk controller and method performed by a disk controller is disclosed which provides a highly efficient means of interrupting the reading or writing of a field in a sector on a magnetic disk for skipping over a servo burst located anywhere within the field. The servo burst may be located at a different location in the fields of successive sectors. In the preferred embodiment, the servo burst skipping operation is controlled by microcode in the disk controller's sequencer RAM, and the servo burst skipping operation is initiated by a servo interrupt signal. The servo interrupt signal is generated by the disk controller when a servo burst is to occur. This servo interrupt signal may be generated at fixed time intervals, using a count from a disk clock, or by counting the bytes in a sector leading to the servo burst.

Abstract: A sequencer map is disclosed which combines a data field and a next-address field into a single field to thereby reduce the word length of instructions required to operate a magnetic disk drive. The combined data and next-address field has two different functions. In one mode, the combined data and next-address field contains a condition code and a next-address. The condition code identifies a condition and instructions to go to a next address in the sequencer map depending on whether the condition is met. In this mode, the next address to be carried out if the condition is met is contained in the combined data and next-address field. In a second mode, the combined data and next-address field is used to store information which is then output for comparison to information read from the disk, or for writing onto the disk during formatting, or which is not used.

Abstract: A novel disk controller and method performed by a disk controller is disclosed which provides a highly efficient means of interrupting the reading or writing of a field in a sector on a magnetic disk, for skipping over a servo burst located anywhere within the field. The servo burst may be located at a different location in the fields of successive sectors. In the preferred embodiment, the servo burst skipping operation is controlled by microcode in the disk controller's sequencer RAM, and the servo burst skipping operation is initiated by a servo interrupt signal. The servo interrupt signal is generated by the disk controller when a servo burst is about to occur. This servo interrupt signal may be generated at fixed time intervals, using a count from a disk clock, or by counting the bytes in a sector leading to the servo burst.