JPS6357797B

A method and apparatus for performing dot matrix printing in which the storage capacity of a memory used for storing character patterns is significantly reduced and the accompanying decoding process is quite simple. Character patterns to be printed are coded in patterns of normal and half-shifted dots, and data representing both types of dots is stored in a read only memory. Half-shift instructions are stored in the memory to identify which dots are to be printed at half-shifted positions located between adjacent columns in a matrix used as a reference from which the character pattern is encoded. Several half-shift instructions are stored for each row with each instruction corresponding to a plurality of adjacent dot locations in the associated row. In reading out data from the memory, each half-shift instruction is effective until the location of the next half-shift instruction is reached. In a preferred embodiment, the character patterns are encoded so that the memory can be read bi-directionally, printing in two directions.