GB1412467A - Control system for a high speed page printer - Google Patents

Abstract

1412467 Control of printers MULLARD Ltd 23 Jan 1974 [23 Oct 1972] 48712/72 Heading G4H The invention relates to circuitry for feeding printing signals to a dot-matrix page printer. Each character is in the form of a 7 Î 5 matrix on a 17-line, 64-character page, corresponding characters on each line being built up simultaneously by the simultaneous printing of corresponding dots in each character in the order shown in Fig. 2. The paper is moved continuously so that the printed characters are skewed; each dot in a row may be duplicated for clarity. Each character to be printed is input via K1 in ASC11 code to shift registers SR1, SR2 alternately, and then used to access a dot matrix character generator ROM which outputs a column at a time under the control of a counter Cl. The row dots in each column are selected by gates G13-G19 enabled by a decoder Dl under the control of a column counter C2; ROM is accessed 35 times for the 17 characters to be printed together, when C1 and C2 hold their counts until the required 17 bits have passed through one of G13-G19. These bits are fed alternately to 17-stage registers SR3, SR4 to provide outputs 1-17 via gates G20- G36 or G37-G53 to the print head. A row-scan ROM may be used (Fig. 6, not shown) the choice of ROM also determining the matrix size. The capacity of SR3, SR4 corresponds to the number of lines per page.