Browse Prior Art Database

Program to Convert Relative Address Encoded Defective Bubble Minor Loops to Compressed Skip Map

IP.com Disclosure Number: IPCOM000047111D
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Chen, CH: AUTHOR

Abstract

Fig. 1 is a flowchart illustrating the various steps involved in converting data stored in an uncompressed intermediate skip map (ISM) of Fig. 2 into a compressed, interleaved two-tier skip map of Fig. 3. The data that is encoded in the ISM relates to (1) defective minor loop positions of a bubble memory and (2) format information relative to particular control bytes, such as the ID byte and skip bytes that are to be used in formatting data that is stored in the bubble memory. Fig. 4 shows the storage of defective data in encoded form in a 128-byte programmable read-only memory (PROM) which is associated with one 9-chip bubble module of the storage system.

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Program to Convert Relative Address Encoded Defective Bubble Minor Loops to Compressed Skip Map

Fig. 1 is a flowchart illustrating the various steps involved in converting data stored in an uncompressed intermediate skip map (ISM) of Fig. 2 into a compressed, interleaved two-tier skip map of Fig. 3. The data that is encoded in the ISM relates to (1) defective minor loop positions of a bubble memory and (2) format information relative to particular control bytes, such as the ID byte and skip bytes that are to be used in formatting data that is stored in the bubble memory. Fig. 4 shows the storage of defective data in encoded form in a 128-byte programmable read-only memory (PROM) which is associated with one 9-chip bubble module of the storage system. Each address position of the PROM contains 8 bits, four of which define the displacement of a bad minor loop from the previous bad minor loop (modulo 16) with the remaining four bits defining which bit position or chip in the 9-bit byte contains the defect. Data from the PROM of Fig. 4, along with information about the format of the data to be stored in the bubble memory, is used to establish the ISM. In the map shown in Fig. 2, four bits are employed to define the type of byte that is to be stored at each of the byte positions of the memory. Good data byte positions store a four zero pattern, i.e., 0000, and hence the ISM will contain a vast majority of that pattern.

Data from the PROM of Fig. 4, designated defect m...