Abstract: The arbitrating method is based on the classification of the users into different categories, and the assignment to all users in a category of an identical privilege level which characterizes the interruption capability of the users in the category. A task performed by a selected user in a category can only be interrupted for granting access to the resource to a user in a category having a higher privilege level. Also a normal preference level is assigned to each user within a category, which determines the selection order of the users in the category. The privilege level of a user category combined with the preference level of each user constitutes the priority level of the user. The access to the resource is granted to a selected user having the highest priority level.

Abstract: The method and apparatus for correcting one B-bit block in error in a memory organized in words comprising N B-bit blocks consist of appending to the data bits to be written into the memory words a limited number of error correction bits computed from a depopulated parity check matrix which gives the capability of only correcting one block in error and improving the memory failure rate by cyclically reading each word, correcting a block found in error if any and writing the corrected data bits with the corresponding error correction bits in place of the read word.

Abstract: Synchronization apparatus in interconnected units of a data processing system resynchronize received bits from a bus with the internal clock of the unit. The synchronization arrangement has two identical synchonization devices which alternately process received strobe pulses which are used for sampling data bits into a first register, generating a gating pulse on one output and a validation pulse on a second output. In response to the gating pulse, bits stored in the first register are transferred to a second register to be available for use by processing logic in synchronism with the internal clock signal. The synchronization devices include two parallel synchronization circuits operating in opposite phase so that the detection of one strobe pulse by one circuit: automatically disables the other one.