US 4,723,181 A · Tape memory with integral disk index on reel

Abstract

A peripheral memory controller controls a helical scan magnetic tape recorder so as to record and play back data files in parallel tracks on a magnetic tape. The tape is contained in a cassette having a magnetic disk fixably mounted on one reel of the cassette so that the movement of the tape and rotation of the disk are simultaneous. The peripheral memory controller refers to a file allocation table stored in one (or more) tracks on the disk, in order to correlate data file descriptions with track locations on the tape. A disk head rapidly scans the file allocation table disk track(s) within just one (or a few) revolutions of the disk while transmitting the contents of the table to the peripheral memory controller. The controller deduces therefrom the tape track location of a particular data file and commands the tape to be transported to that location in order to access that file. In another embodiment, sub-file allocation tables, each describing the tape track location of each sub-file within a given data file, are recorded in other disk tracks whose locations are recorded, in turn, in the file allocation table disk track. In order to take advantage of the co-movement of the tape and the disk, each sub-file allocation table stores the names of sub-files whose tape track locations fall within a length of tape covered during one rotation of the reel and disk, so that each sub-file allocation table disk track may be scanned completely while maintaining the position of the tape within the tape location range of the corresponding sub-file allocation table.

Claims12

Dependent claims

A mass memory useful with an external host computer whereby said external host computer may store in and retrieve from said memory large quantites of data, said memory comprising:

(I) an insertable cassette, comprising:
(a) at least one tape reel,
(b) a length of magnetic tape windable around said reel,
(c) a rotary storage disk mounted concentrically over said one tape reel and being rotatable therewith;
(II) a helical scan cassette recorder adaptable to receive said insertable cassette, said recorder comprising:
(a) first means for recording onto said tape, and playing back from said tape, blocks of information,
(b) second means for recording data onto, and playing back data from said disk,
(c) means for rotating said reel so as to transport said tape and rotate said disk,
(III) peripheral memory controller means connectable to said external host computer, said controller means for:
(a) accepting a command from said host computer, said command being either a retrieve command or a store command, said command containing at least the name of a selected one of said information blocks,
(b) whenever said command is a store command, causing said second means to write the name of said selected one of said information blocks, together with data relative to a corresponding location on said tape, in at least an arcuate track on said disk, and receiving data comprising said selected information block from said host computer and causing said first means to record said data comprising said selected information block on said tape at said corresponding tape location;
(c) whenever said command is a read command, inspecting through said second means the data stored in a least said arcuate track on said disk, and deducing therefrom the corresponding tape location of said selected information block, causing said means for rotating to transport said tape to said corresponding tape location, and causing said first means to begin playing back the data stored at said corresponding tape location.

9 more elements

A mass memory connectable to an external host computer whereby said external host computer may store in and retrieve from said mass memory large quantities of data, said mass memory comprising:

a take-up reel adapted to wind a length of magnetic tape;
a helical-scan rotating head drum adapted to contact said magnetic tape and record thereon and playback therefrom information blocks in respective locations on said tape;
an information-storing disk concentrically mounted on said take-up reel;
a memory controller connected to receive read commands and write commands from said host computer, said memory controller adapted to facilitate the storage or retrieval of an information block selected by said host computer to or from said mass memory, respectively, said memory controller comprising means for:
(1) whenever a write command is received from said host computer, writing the name of the selected information block together with data relative to a corresponding tape location in at least one arcuate track on said disk, receiving said selected data block from said host computer and causing it to be recorded on said tape at said corresponding tape location;
(2) whenever a read command is received from said host computer, inspecting the contents of at least to said corresponding tape location, causing said head drum to play back therefrom said selected information block, and transmitting said selected information block to said host computer.

3 more elements

Dependencies are inferred from the claim text.

Tape memory with integral disk index on reel

Life of this patent

Tape memory with integral disk index on reel

Life of this patent

Abstract

Claims12