CompuServe Messages

Brian, The Rainbow's method of selecting character sets entirely duplicates the use of character sets by DEC's VT100 terminal. I would imagine that it is rooted in history and that DEC is stuck with the system because it was developed years ago. Anyway, the Rainbow does have two main character sets, called G0 and G1, and two "alternate" character sets, called G2 and G3, but you can't change G2 and G3; "they" are the default character set from set-up, meaning either the U.S. character set with a number sign above the 3 or the U.K. character set with a pound sign there. (The Brits get to keep our dollar sign above the 4.) You can define G0 to be the U.K. character set by sending ESC (A, the U.S. character set with ESC (B or the line drawing set with ESC(0. Similarly, you select G1 with ESC )A, ESC )B or ESC )0. Now, what I think you wanted to know: You can change from G0 to G1 by sending control-N (ASCII 14) to the screen. You can change back from G1 to G0 again by sending control-O (ASCII 15) to the screen. You can also select a single character from G2 by sending ESC N or the ASCII character 142 to the screen, and a single character from G3 by sending ESC O (the letter, not the number) or the ASCII character 143. Since G2 and G3 are just the set-up character sets, this isn't particularly useful. I would guess that the VAXen that your computer talks to are programmed to keep graphics in either G0 or G1 and ASCII in the other, so they can use control-N and control-O to shift back and forth. — Carl