Seeking: IBM Coding Forms

On Thu, Feb 10, 2011 at 6:36 PM, Richard Hadsell <hadsell at blueskystudios.com> wrote: As many other have asserted, the 80-column part? Yes. It's also handy for displaying part of a page to be typed at "pica" sizes (10 chars to the inch on a 8.5" page with 0.25" margins). The length, though, took a while to catch up. The VT50 (1975) was 80 columns (its predecessor, the VT05 (1970) was 72, like an ASR-33), but only 12 lines. It was the VT52 (1976) that was AFAIK, DEC's first 80x24 terminal. Over in IBM land, there's the 3277 terminal, which I always thought was 80x24, but I found a mention of a "model 1" with 40x12. There are also a couple of external factors that most likely influenced the path to 80x24 - CRT aspect ratio and memory geometry. Inexpensive CRTs were (are still) 4:3 aspect ratio. The DEC VT50 was 12 lines, but AFAIK, they were double-spaced on the screen, spread out across the horizontal axis, not crushed together (like an unenhanced VT100 in 132-column mode). They certainly didn't go out and make a custom CRT to neatly fit 80x12. Memory geometry comes into play when designing an inexpensive character buffer for the display. If there had been an arbitrary reason to support, say, 80x30, perhaps the designers of the 1970s might have taken a different path, but with 80 columns a preferred width due to previously mentioned factors, 80x12 == 960 bytes (under 1K) and 80x24 == 1920 bytes (under 2K) and further, 80x25 == 2000 bytes (still under 2K, but it was a while until the "25th status line" feature crept in). I was merely a user of terminals in the 1970s, not a designer, but this place is as good as any to find folks who might have been there at the time and can confirm/deny any speculations from their own experience. -ethan