Abstract: Disclosed is a control method for writing or reading sequentially a plurality of blocks of data for a storage device using a recording medium, such as a photo disk, with a number of recording blocks each having a unique address. In writing data, a plurality of data blocks to be written concurrently are given in their pointer fields the first address indicating the same alternative block, and these data are written in consecutive recording blocks on the recording medium. If blocks with write errors are detected, the data blocks corresponding to the error blocks are written sequentially in an alternative area starting from the first address, after replacing the pointer fields with the second address indicating the defective blocks, respectively. This allows the access of the alternative blocks for defective blocks by detecting the pointer address within the pointer fields of normal blocks preceding and following each of the defective blocks during the data reading operation.

Abstract: An information transfer apparatus for connecting between plural channels and input/output control devices in a computer system, comprising a bundle of signal lines with which said channels are connected, said bundle of signal lines including plural signal lines provided respectively for said plural channels so as to effect the time-shared connection between said plural channels and input/output control devices therethrough.

Abstract: A method of controlling a rotary memory for preventing failure to read a recorded information block during reading of the contents of the memory. In the method, a second marker is provided separately from a first marker representing the starting point of each recorded information block so as to achieve the desired missing-free read control of the rotary memory.