Control apparatus for hammer type impact printer

Claim 1

A control apparatus for a proportional spacing printer constructed to selectively print with first and second fonts comprising a common set of characters, widths of at least some characters in the first font differing from widths of respective characters in the second font, comprising: read-only storage means for pre-storing first proportional space data for the first font; read-write storage means for storing second proportional space data for the second font; buffer means for temporarily storing character codes corresponding to said characters respectively and the second proportional space data input thereto; discrimination means operatively connected to the buffer means for discriminating the character codes from the second proportional space data; transfer means operatively connected to the buffer means and discrimination means for transfering the second proportional space data discriminated by the discrimination means from the buffer means to the read-write storage means; and control means for controlling the printer to perform proportional printing with the first font using the first proportional space data stored in the read-only storage means and to perform proportional printing with the second font using the second proportional space data stored in the read-write storage means; the transfer means being further operatively connected to the read-only storage means for initially transferring the first proportional space data from the read-only storage means to the read-write storage means, the transfer means subsequently transferring the second proportional space data from the buffer means to the read-write storage means to replace respective data in the read-write storage means, the second proportional space data comprising data for only those characters of the second font having widths differing from widths of respective characters in the first font.