Digital data storage methods and apparatus

Claim 3

The method of storing a predetermined bit pattern as claimed in claim 1 in which said first index bit pattern is modified in accordance with said second index bit pattern to provide a third index bit pattern and said bit pattern representing said predetermined address and said second index bit pattern are then stored in a catalog memory at a location determined in accordance with said second index bit pattern and said third index bit pattern.

Claim 4

The method of storing a predetermined bit pattern as claimed in claim 1 in which the transforming of said key bit pattern into said first and second index bit patterns comprises the steps of: storing said key bit pattern in a key bit pattern shift register; and shifting said key bit pattern from said key bit pattern shift register into a logic circuit which emits a corresponding bit stream into a first index bit pattern register and a second index bit pattern register; the operation of said logic circuit being controlled at least in part by contents of at least one of said first index bit pattern register and said second index bit pattern register.

Claim 5

The method of storing a predetermined bit pattern as claimed in claim 2 in which the transforming of said key bit pattern into said first and second index bit patterns comprises the steps of: storing said key bit pattern in a key bit pattern shift register; and shifting said key bit pattern from said key bit pattern shift register into a logic circuit which emits a corresponding bit stream into a first index bit pattern register and a second index bit pattern register; the operation of said logic circuit being controlled at least in part by contents of at least one of said first index bit pattern register and said second index bit pattern register.

Claim 6

The method of storing a predetermined bit pattern as claimed in claim 3 further comprising the step of passing a bit stream shifted from said first index bit pattern register through a second logic circuit which emits a corresponding bit stream into said second index bit pattern register, the operation of said second logic circuit being controlled at least in part by contents of at least one of said first index bit pattern register and said second index bit pattern register.

Claim 7

The method of storing a predetermined bit pattern as claimed in claim 2 further comprising the step of passing the bit stream shifted from said first index bit pattern register through a second logic circuit which emits a corresponding bit stream into said second index bit pattern register, the operation of said second logic circuit being controlled at least in part by contents of at least one of said first index bit pattern register and said second index bit pattern register.

Claim 8

The method of storing a predetermined bit pattern as claimed in claim 2 in which the production of said third index bit pattern comprises the steps of: adding to said first index bit pattern predetermined, shifted portions of said second index bit pattern; and adding thereto said second index bit pattern.

Claim 9

The method of storing a predetermined bit pattern as claimed in claim 4 in which the production of said third index bit pattern comprises the steps of: adding to said first index bit pattern predetermined, shifted portions of said second index bit pattern; and adding thereto said second index bit pattern.

Claim 10

The method of storing a predetermined bit pattern as claimed in claim 6 in which the production of said third index bit pattern comprises the steps of: adding to said first index bit pattern predetermined, shifted portions of said second index bit pattern; and adding thereto said second index bit pattern.

Claim 11

A digital data storage system comprising a storage memory containing a plurality of records each of which is located at a predetermined record address and a catalog memory containing a plurality of entries each of which corresponds to one of said records in said storage memory and comprises the address thereof, at least some of said entries further comprising a chain pointer address designating another one of said entries and a confirmation index derived from the corresponding record.

Claim 12

A digital data storage system comprising a storage memory containing a plurality of records each of which is located at a predetermined record address and a catalog memory containing a plurality of entries each of which corresponds to one of said records in said storage memory and comprises the address thereof, at least some of said entries further comprising a chain pointer address designating another one of said entries and a confirmation index derived from the corresponding record.

Claim 13

A digital data storage system as claimed in claim 10 further comprising entry index generating means for deriving from a record a chainhead entry address and a confirmation index.

Claim 14

A digital data storage system as claimed in claim 11 in which said entry index generating means comprises analyzer means for deriving keys from succesive ones of said reords, transformer means for transforming said keys into corresponding key transforms, dissecting means for dissecting said key transform's into segments, and combining means for combining predetermined ones of said key transform segments in accordance with a predetermined logical function, whereby to produce in response to each record received by said analyzer means a chainhead entry address and a confirmation index.

Claim 15

A digital data storage system as claimed in claim 12 in which said transformer means comprises a key shift register, a plurality of key transform segment shift registers, and at least one logic circuit constructed and arranged to modify one at a time of said keys in accordance with a predetermined logical function of at least part of the contents of at least one of said key transform segment shift registers as said one at a time of said keys is shifted bit-by-bit from said key shift register.

Claim 16

A digital data storage system as claimed in claim 13 in which said logical function is the EXCLUSIVE OR function.

Claim 17

A digital data storage system as claimed in claim 14 in which said combining means comprises adding means for adding together binary numbers representing the contents of said key transform segment shift registers and at least one modified version of the contents of one of said key transform segment shift registers.