Apparatus for the detection and correction of errors for a rotational storage device

Claim 2

Error detection and correction apparatus coupled with a rotational storage device, said device storing a plurality of pages in a record, each page including data, a reverse and a forward pointer, said reverse pointer linking to the previous page in said record and said forward pointer linking to the next page in said record, said apparatus comprising: A. means for comparing the reverse pointer of the current page addressed by said apparatus and the address of the page last addressed by said apparatus; and B. means for generating an error signal when said reverse pointer of the current page addressed by said apparatus and said address of the page last addressed by said apparatus are dissimilar.

Claim 3

Apparatus as defined in claim 1 further comprising: A. means responsive to said error signal for addressing the page last addressed by said apparatus; and B. means for addressing the pages of said record in reverse order from said page last addressed by said apparatus.

Claim 4

Apparatus as defined in claim 2 further comprising: A. means for transferring data in said pages between said device and said apparatus; and B. means for disabling said means for transferring said data in response to said error signal.

Claim 5

Apparatus as defined in claim 3 further comprising: A. means for generating a first signal when the address of the current page addressed and the reverse pointer of the first page addressed are similar; and B. means enabling said means for transferring said data in response to said first signal.

Claim 6

Error detectioN and correction apparatus coupled with a rotational storage device, said device storing a plurality of pages in a record, each page including data, a reverse pointer and a forward pointer, said reverse pointer linking to the previous page in said record and said forward pointer linking to the next page in said record, said apparatus further coupled with data processor means which processor means includes storage means, so that said pages are transferred from said processor means to said device during a write operation and so that said pages are transferred from said device to said processor means during a read operation, said apparatus comprising: A. a present pointer register for storing a present page address of said device to or from which present page address, one of said pages is to be transferred; B. means for loading said present pointer register with the pointer of said present page; C. reverse pointer register for storing the reverse pointer of said present page; D. a forward pointer register for storing the forward pointer of said present page; E. means for loading said reverse and forward pointer registers with the reverse and forward pointers of said present page; F. means for transferring said pages between said device and said processor means; G. means for updating said reverse and forward pointers stored in said reverse and forward pointer registers after said present page is operated upon and after said present page address is changed; and H. means for producing an error signal when said reverse pointer stored in said reverse pointer register and the previous present page pointer are dissimilar, said error signal indicating an error in one of said pointers of said pages in said record.

Claim 7

Error detectioN and correction apparatus coupled with a rotational storage device, said device storing a plurality of pages in a record, each page including data, a reverse pointer and a forward pointer, said reverse pointer linking to the previous page in said record and said forward pointer linking to the next page in said record, said apparatus further coupled with data processor means which processor means includes storage means, so that said pages are transferred from said processor means to said device during a write operation and so that said pages are transferred from said device to said processor means during a read operation, said apparatus comprising: A. a present pointer register for storing a present page address of said device to or from which present page address, one of said pages is to be transferred; B. means for loading said present pointer register with the pointer of said present page; C. reverse pointer register for storing the reverse pointer of said present page; D. a forward pointer register for storing the forward pointer of said present page; E. means for loading said reverse and forward pointer registers with the reverse and forward pointers of said present page; F. means for transferring said pages between said device and said processor means; G. means for updating said reverse and forward pointers stored in said reverse and forward pointer registers after said present page is operated upon and after said present page address is changed; and H. means for producing an error signal when said reverse pointer stored in said reverse pointer register and the previous present page pointer are dissimilar, said error signal indicating an error in one of said pointers of said pages in said record.

Claim 8

Apparatus as defined in claim 5 wherein said means for updating comprises: A. means for transferring the pointer of the present page operated upon to said reverse pointer register after said present page is operated upon; and B. means for transferring the contents of said forward pointer register to said present pointer register after said pointer of the present page operated upon is transferred to said reverse pointer register.

Claim 9

Apparatus as defined in claim 6 further comprising: A. means for addressing said device with the previous page pointer utilized to produce said error signal; and B. means responsive to said error signal for transferring said pages of said record in reverse order starting with the page indicated by said previous page pointer utilized to produce said error signal.

Claim 10

Apparatus as defined in claim 7 wherein said means responsive to said error signal for transferring said pages comprises: A. means for disabling the transfer of the contents of said forward pointer register to said present pointer register; and B. means for transferring the contents of said reverse pointer register to said present pointer register.

Claim 11

Apparatus as defined in claim 8 further comprising means for inhibiting transfer of data in the pages of said record starting with the page indicated by said previous page pointer utilized to produce said error signal.

Claim 12

Apparatus as defined in claim 9 further comprising means for reenabling transfer of data in pages of said record after said pages are addressed in reverse order when the contents of said present pointer register are similar to the reverse pointer of the first page of said record addressed by said present pointer register.

Claim 13

Apparatus as defined in claim 8 further comprising: A. a first reverse pointer register coupled to said reverse pointer register for storing the first reverse pointer of said record received by said reverse pointer register; B. means for disabling transfer of data of said page between said device and said processor means after said error signal is generated; and C. means for enabling transfer of data of said pages between said device and said processor means after the coNtents of said first reverse pointer register and said present pointer register are similar.

Claim 14

Error detection and correction apparatus coupled with a rotational storage device, said device storing a plurality of pages in a record, each page including data, a reverse pointer and a forward pointer, said reverse pointer linking to the previous page in said record and said forward pointer linking to the next page in said record, said apparatus comprising: A. a present pointer register for addressing the current page to be operated upon; B. a reverse pointer register for storing the address of the page immediately preceding said current page; C. a forward pointer register for storing the address of the page immediately following said current page; D. means for loading said present, reverse and forward pointer registers with said present, reverse and forward pointers respectively; E. a previous present pointer register coupled to said present pointer register for storing the address of the previous current page addressed; F. means for transferring the contents of said forward pointer register to said present pointer register after the current page addressed is operated upon; G. means for generating an error signal when the contents of said reverse pointer register and the contents of said previous present pointer register are dissimilar; H. means for transferring the contents of said previous present pointer register into said present pointer register in response to said error signal; and I. means for transferring the contents of said reverse pointer register into said present pointer register after the page indicated by said present pointer register in response to said error signal is operated upon.

Claim 15

Error detection and correction apparatus coupled with a rotational storage device, said device storing a plurality of pages in a record, each page including data, a reverse pointer and a forward pointer, said reverse pointer linking to the previous page in said record and said forward pointer linking to the next page in said record, said apparatus comprising: A. a present pointer register for addressing the current page to be operated upon; B. a reverse pointer register for storing the address of the page immediately preceding said current page; C. a forward pointer register for storing the address of the page immediately following said current page; D. means for loading said present, reverse and forward pointer registers with said present, reverse and forward pointers respectively; E. a previous present pointer register coupled to said present pointer register for storing the address of the previous current page addressed; F. means for transferring the contents of said forward pointer register to said present pointer register after the current page addressed is operated upon; G. means for generating an error signal when the contents of said reverse pointer register and the contents of said previous present pointer register are dissimilar; H. means for transferring the contents of said previous present pointer register into said present pointer register in response to said error signal; and I. means for transferring the contents of said reverse pointer register into said present pointer register after the page indicated by said present pointer register in response to said error signal is operated upon.

Claim 16

Apparatus as defined in claim 12 further comprising: A. a first reverse pointer register coupled to said reverse pointer register for storing the first reverse pointer of said record received by said reverse pointer register; B. means for disabling the transfer of data between said device and said apparatus after said error signal is generated; and C. means for enabling transfer of data between said device and said apparatus after said error signal is generated and after the contents of said first reverse pointer register and said present pointer register are similar.