Abstract: In a system for transferring data between a host device and a target recording medium, a buffer interface control unit includes a host direct memory access (DMA) unit for transferring data from the host unit to a buffer memory. The host DMA unit accesses a first set of prescribed noncontinuous buffer memory storage locations to store the data transferred from the host unit in a predetermined buffer format that includes additional sets of prescribed storage locations interspersed with the first set of data storage locations for the storage of error code characters pertaining to the data. The host DMA unit also transfers error correction code characters pertaining to the data to one of the additional sets of prescribed storage locations. The buffer interface control unit further includes a target DMA unit for transferring data from the buffer memory to a write interface unit.

Abstract: The specification discloses a method and apparatus for providing speed control and rotational indexing of a disc recorder, based upon a particular use of a plurality of electrical pulses produced, for example, as the slots of a slotted wheel, axially coupled to a recording disc, pass a transducer. The primary repetition rate of pulses in response to equally-spaced slots is used for speed control of the recording disc. A secondary pulse rate occurring between two successive pulses resulting from adjacent slots with different spacing is used to establish an index pulse correlated with a reference point on the disc.