Data transfer apparatus for use with a flexible magnetic disk or the like

Abstract

A data transfer apparatus is disclosed as typified by a floppy disk drive which, together with one or more like devices, is daisy chained to a central processor unit via a controller. Each disk drive comprises a disk motor for driving a record disk under the control of a disk motor drive circuit, a head motor for incrementally moving a transducer head radially of the record disk under the control of a head motor drive circuit, and a read/write circuit for processing data read from, or to be written on, the record disk via the transducer head. Also included in each disk drive is a sensor control circuit associated with an optical sensor assembly for producing a DISK PRESENCE signal representative of the presence or absence of the record disk in the disk drive. In order to avoid waste of power, at least one, preferably all, of the disk motor drive circuit, head motor drive circuit, and read/write circuit is connected to an external power line via a power control switch which is closed in response to the DISK PRESENCE signal only when the record disk is loaded in the disk drive. Additional embodiments are disclosed wherein the power control switch responds not only to the DISK PRESENCE signal but also to a standard MOTOR ON signal or DRIVE SELECT signals, or to both, which are supplied from the host equipment.