Epf recognizes printer control strings of the type recognized by col(1), viz., those for half-line forward and reverse, and full-line reverse motions (ESC-9, -8, and -7, respectively), and those for the special characters (SO-<single printable character>-SI).
Epf implements the printer control and graphics needed for tbl(1) and neqn(1).
For Epson Elite mode (12 characters per inch), as above, except use the nroff(1) option, -Tepson-12.
The nobs(1) filter is not needed if the printer can overstrike a character with itself, but even if not needed, it may cut down on clatter.
J.A. Rupley, University of Arizona
..{uunet | ucbvax | cmcl2 | hao!ncar!noao}!arizona!rupley!local
rupley!local@megaron.arizona.edu
Epson LQ printers with tractor feed cannot usefully execute full- or half-line reverse motions. Thus col(1) processing is essential, to convert reverse to forward motions. There is no thought of finer grain than one-character horizontal and half-line vertical.
The widths of the user-defined characters are slightly greater than the 10-character-per-inch width of the Epson Pica font. The difference is small enough to allow mixing of graphics and Pica. However, mixing of user-defined characters with 12-character-per-inch Epson Elite can give noticeable loss of registration.
The graphics are good, but like most things probably can be made better.
Epf of course must be written to be compatible with the coding of the driver tables. Epf and the driver tables constitute a unit. There are various versions of nroff(1). The driver tables are written for the "old" nroff.
Compilation of the driver tables requires the Townsend package.
Nroff(1) overstrikes the SO,SI delimiters of a special character representation, moving the overstruck special character improperly to the left. Fix by filtering the raw nroff output to remove SO-<bksp> and SI-<bbksp> sequences.
Col(1) does not pass a file-ending SO,SI sequence, specifically, a printer reset command. Fix by filtering the raw nroff output or ensuring reset of the printer in the printer interface.
Printer implementations are messy enought to ensure perpetual bugginess.