Abstract: A disk drive system provides a low height device by mounting a circuit board or boards containing the electronic circuitry in the same enclosure with the head-disk assembly (HDA). The drive actuator mechanism is positioned at one side of one end of the enclosure and the circuit board or boards are positioned at the other side of that end of the enclosure. A gasket seals the HDA from contaminants, while the enclosure protects the electronic circuitry and cables from physical damage, electrostatic charges and electromagnetic interference. The circuit board or boards can be removed from the enclosure without removing the entire disk drive from the using system, and the entire drive assembly can readily be removed from the using system for replacement or use in another system.

Abstract: A peripheral device control system includes a single flash memory having a changeable portion for storing firmware for controlling the peripheral device and a preprogrammed portion containing control code. When it is desired to modify the changeable firmware, the control code is read from the flash memory to a storage area in the using system and is used to control the loading of the modified firmware in the flash memory.

Abstract: A Split (Data) Field Zone Density Recording (ZDR) on a disk drive system is implemented using a disk controller with a servo timer. The servo timer estimates the periodic occurrences of the servo sectors, thereby eliminating the need for look-up tables and complex operating sequences. Whenever a servo sector is detected, a reset signal is sent to the servo timer which then estimates when the next servo sector can be expected. When the next servo sector is expected, the servo timer signals the disk controller. If this return signal from the servo timer occurs during a read/write of a split data sector, the read/write operation is suspended. The disk controller then waits for the next servo sector. After detecting the next servo sector, another reset signal is sent to the servo timer. The disk controller then synchronizes with the data bit stream and subsequently reads the remaining portion of the split data sector.