RFC 320

The Title Block 🎀

okay so bestie, first things first: this is RFC 320, titled Workshop on Hard Copy Line Graphics 💖

• Network Working Group
• Author: R. Reddy, CMU
• NIC: 9350
• Date: 27 March 1972
• Obsoletes / Updates: none listed 🌸
• Category / Status: not stated in the original 🫶

Workshop on Hard Copy Line Graphics 🖨️✨

okay so at CMU the team just hooked up a Xerox Graphic Printer (ex-LDX) to a PDP-10, and they used a PDP-11 as an intelligent controller for the printer 🤖💅 The special interface and data structures let the PDP-11 generate each scan line as it's needed, so they never have to brute-force generate the bit image for the whole page. literally genius 😭

The attached pages were made with this system, using a document generation program and a character set design program. ngl this is something personal 🦋

okay so after several requests, they're hosting a one day workshop on the XCRIBL system 🎀 It's happening in 3124 Science Hall at Carnegie-Mellon University on April 12. The agenda is attached. If you're interested in coming or sending someone, reach out to any of these people for info or local arrangements:

• Dr. D. R. Reddy (412-621-6200 ext. 149)
• Mr. Mack Hicks (412-687-5846)
• Miss M. Kostkas (412-626-2600 ext. 141)

For rooms, you can book at the Webster Hall Hotel (412-621-7700) or the Civic Center Motor Hotel (412-683-6700). Both are within walking distance of Carnegie-Mellon University 🧚

Carnegie-Mellon University Agenda 📅

CARNEGIE-MELLON UNIVERSITY

WORKSHOP ON HARD COPY LINE GRAPHICS

                             April 12

                              Morning
             Document Generating Languages and Systems

9:00-9:30    Raj Reddy          Overview of the XCRIBL system
9:30-10:20   Joe Newcomer       Languages for Document Generation
10:20-10:30  Coffee Break
10:30-12:00  Examples of Document Generation
                          Letter Producing Systems
                          Technical Report Production
                          A Graphics and Gray Scale Image System

                             Afternoon
                          Systems Support

12:00-1:45  Lunch               Character Sets (Generation and
1:45-2:45   Lee Erman           Modification)
2:45-3:00   Coffee Break
3:00-4:00   George Robertson    The PDP-11 Support System
4:00-5:00   Bill Broadly and    The PDP-11 XGP Interface (Hardware)
            Jack Wright

                              Evening
                     Session for the "Hackers"

7:30-10:30  Discussion session of as yet unsolved issues and
            possible hardware-software solutions.

XCRIBL System 💜

COMPUTER SCIENCE DEPARTMENT CARNEGIE-MELLON UNIVERSITY

okay so what you're reading right now is a computer printout made by the XCRIBL system 🖨️✨ Normal computer printers don't have typefaces like this one, and they can't change typefaces either. Conventional printers also can't print character sets where the center-to-center distances aren't all the same 🙈 The machine that printed this doc is a facsimile copying machine that Xerox built a few years ago. The CMU computer science department designed and built the interface that hooks it up to a minicomputer (PDP-11), which is then linked to a big computer, the PDP-10. The setup has been working since January 🌈

The Xerox Graphic Printer (XGP) works kind of like Xerox office copiers, but with a twist. Instead of reflecting light off a printed page the way a copier does, the XGP uses a cathode ray tube (think old TV tubes) as its light source 📺 The image is drawn as a series of dots on the CRT at a resolution of 12 dots per inch. That line of dots gets reflected onto a selenium drum, which electrostatically attracts fine black powder to the exposed selenium areas. The powder is transferred to a moving sheet of paper, and then a fuser melts it onto the paper. it's giving chemistry class but make it iconic 🔥

To print any character, the pattern of dots for that character has to be entered into the computer, along with an indicator of what the pattern represents. So the team wrote a program to design character sets 🧚 It draws a grid on a display terminal, and each box in the grid stands for one dot in the final Xerox output. Dots can be set or unset, and the character gets redrawn on the display as often as you want. Because it's so easy, designing a character set becomes a genuinely fun task, and you can change any part of any character 💅

The XGP can also draw lines and gray scale images. The AI group is using it to print pictures of faces and speech spectrograms 👑 The range of possible uses is boundless. periodt 🦋

[This RFC was put into machine readable form for entry] [into the online RFC archives by Helene Morin, Via Genie 10/99] 🫶