Abstract: A data recording device including recording media having a set of at least two alternate regions thereon for each data segment, whereby each data segment has a corresponding set of at least two alternate regions on the recording media; a transducer positionable to write data on and read data from the recording media; and a controller for recording one or more data segments on the recording media in response to one or more write commands, the controller including a selector wherein for each of said one or more data segments the selector selects one region from the set of alternate regions corresponding to that data segment and positions the transducer to write that data segment on the selected region. To reduce the access time for each write operation, the selector selects the one region from the set of alternate regions based on shortest access time required to access each of the regions in the set of alternate regions for recording data.

Abstract: A data transfer management method is provided for transferring data between nodes of a multi-node communication system. The method provides target nodes with fair opportunity to transfer data to originator nodes in the communication system. The originator node initiates data transfer by establishing a connection with one or more target nodes. The originator node signals target nodes to transfer data by generating and transmitting credit tokens over the network. Before a target node can transfer data to the originator node, it must receive and absorb at least one credit token from the originator. All credit tokens transmitted by the originator node and not absorbed by target nodes return back to the originator node. Each target node is provided with buffer credit tokens up to its quota in a rotating manner.

Abstract: A method for arbitrating conflicting requests for a memory transfer in a multiport memory system including first and second memory ports. The method includes the following steps. First, monitoring the volume of memory transfer requests from the first memory port. Second, partially disabling the second memory port if the memory request volume is greater than a first predetermined volume. And third, reenabling the second memory port when the memory request volume becomes less than a second predetermined volume. Apparatus implementing this method which includes an activity detector, coupled to the first memory port, for generating a bistate signal having a first state when the volume of memory requests by the first memory port exceeds a first predetermined volume and a second state otherwise. Circuits are provided for selectively partially disabling memory requests from the second memory port in response to the bistate signal being in the second state.

Abstract: A disk drive system provides all required synchronization, positioning, validation, and data functions within each disk sector. All of these functions are provided within two zones, a header section and a data section. The header section includes a preamble, a synchronization character and an address field, as well as servo information for track following. The data section of each sector includes a data preamble, a data synchronization character, a bad sector bit map, the data and data redundancy information. The header section of at least one sector in a track includes a short DC-erase field, a transitionless segment which is used in synchronization. To synchronize a read/write head to the disk, the system first detects the DC-erase field. The system next searches for the header premable and synchronization character. If it finds them within predetermined times, it then looks for a valid sector address to complete the synchronization.