Page:A contribution to computer typesetting techniques - tables of coordinates for Hershey's repertory of occidental type fonts and graphic symbols (IA contributiontoco424wolc).pdf/10

 9-track magnetic tape which was processed on the NBS computer via a new program to produce a tape to drive the COM device. This technique allowed us to take advantage of Hershey's character digitizations, while avoiding the use of punched cards for text and typographic instructions - the latter being quite cumbersome.

3. The Digitized Character Set

The starting point for the programmer desiring to produce graphic arts output on CRT devices and plotters is a digitized set of alphabetic and graphic characters. The digitizations should conform to several restrictions: (1) They should be adequate in detail to provide suitable representations of the desired characters; (2) They should not be overly definitive to minimize core requirements on the host computer; and (3) The organization scheme should be flexible so as to allow for modification,replacement, or extension of the character set.

It is our view that the vectored digitizations in this report (which were developed by Dr. A. V. Hershey, Naval Weapons Laboratory, Dahlgren, Va.) conform adequately to these requirements. As to whether these vectored characters are capable of graphic arts quality, it is only necessary to refer to figures 4 et. seq. and to the numerous reports (references 5-8) which have been issued using them, to confirm the capability for quality typographic and graphical composition. The core requirement is the availability of the equivalent of 25000 36-bit words which is not excessive for this data base. Characters can be easily omitted, modified, or added to the list so that the core requirement can be tailored to the problem at hand Figure 15 gives some examples of characters which have been generated locally for use with the NBS typographic routines.

As indicated above the occidental repertory of digitized characters has been in existence since 1967. Unfortunately at the time it was first presented this prodigious effort did not receive the widespread notice it deserved, possibly because the representations of the characters were of such high quality that the casual reader did not realize that they were computer output and not graphic arts displays.

In order to make the digitizations more available and to supply more detailed information on how the characters are generated, the present publication lists the individual character digitizations of the occidental character set and indicates by graphic displays the way in which each character is composed from its digital representation. Needless to say the application of the digitizations is not limited to cathode ray printers. The tables can also be used with other computer driven devices such as digital pen plotters, electrostatic printers, or optical recorders.

4. Description of the Hershey Occidental Repertory

There are 1377 characters in the Hershey set, each of which is assigned a number between 1 and 3296 The characters are described as uniplex, duplex, or triplex according to the number of parallel strokes used in the construction of the character. The description as simplex, complex, or gothic, indicates the extent to which the characters contain tapered segments. Three sizes of characters are available: the principal or normal size (21 raster units high, em = 32), the indexical size (13 raster units high, em = 21), and the cartographic size (9 raster units high).

The appearance of the various alphabets when drawn at a normal typographic scale is shown in figure 6. In addition numerous special characters are available. A listing of these and the associated character numbers is found in Appendix C.