projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 95f51977 | 1 | .\" @(#)e2 6.1 (Berkeley) 5/22/86 |
| 8c38cde6 KD |
2 | .\" |
| 3 | .NH | |
| 4 | Photocomposition | |
| 5 | .PP | |
| 6 | Photocomposition techniques | |
| 7 | can be used to solve some of the problems of typesetting mathematics. | |
| 8 | A phototypesetter is a device which exposes | |
| 9 | a piece of photographic paper or film, placing characters | |
| 10 | wherever they are wanted. | |
| 11 | The Graphic Systems phototypesetter[2] on the | |
| 12 | .UC UNIX | |
| 13 | operating | |
| 14 | system[3] works by shining light through a character stencil. | |
| 15 | The character is made the right size by lenses, | |
| 16 | and the light beam directed by fiber optics | |
| 17 | to the desired place on a piece of photographic paper. | |
| 18 | The exposed paper is developed and typically used | |
| 19 | in some form of photo-offset reproduction. | |
| 20 | .PP | |
| 21 | On | |
| 22 | .UC UNIX , | |
| 23 | the phototypesetter is driven by a formatting program called | |
| 24 | .UC TROFF | |
| 25 | [4]. | |
| 26 | .UC TROFF | |
| 27 | was designed for setting running text. | |
| 28 | It also provides all of the facilities that one needs for | |
| 29 | doing mathematics, such as | |
| 30 | arbitrary horizontal and vertical motions, | |
| 31 | line-drawing, size changing, | |
| 32 | but the syntax for describing these special operations is | |
| 33 | difficult to learn, | |
| 34 | and difficult even for experienced users to type correctly. | |
| 35 | .PP | |
| 36 | For this reason we decided to use | |
| 37 | .UC TROFF | |
| 38 | as an ``assembly language,'' | |
| 39 | by | |
| 40 | designing a language for describing mathematical | |
| 41 | expressions, | |
| 42 | and compiling it into | |
| 43 | .UC TROFF . |