Memory system with single command selective sequential accessing of

Abstract

This addressing system, advantageously for smaller scale data processors with relatively narrow data paths, facilitates transferring pluralities of multibit data words, e.g., storing or fetching the contents of a multidigit register in a calculator. A bidirectional bus couples a controller and a plug-in memory. The controller generates address, data, and command signals. A decoder receives command signals and outputs signals to a program counter (PC) alternatively indicating a normal mode, in which the controller accesses a single specified memory address, or a multiple access mode, in which a predetermined number of sequential addresses are accessed starting at a specified address. In response to selective command decoder output, the PC alternatively may store received addresses, output stored count values to the controller or to a memory array, or increment the count value in synchronism with data transfers to/from multiple memory locations. The decoder, PC, and memory array are contained within the portable memory module's housing, which may be mounted in another housing containing the controller. In a ROM embodiment, the mounted memory is powered directly from a source in the controller housing. In a RAM embodiment, the module's housing includes a power switching circuit and an internal battery to provide uninterrupted power to the read/write memory cells irrespective of whether the module is mounted or detached.