The Terminals Wiki

I have a TeleVideo 955 with manual. It's a neat terminal. It's got three socketed ROMs: one for the character generator, one for the firmware, and a third one for user-supplied firmware, which the manual documents an escape sequence to invoke. (The manual documents the signature expected for the ROM but doesn't describe any of the other things someone would need to write a user-supplied ROM.) As supplied, the third one contains a rudimentary calculator, but it's replaceable. The CPU is a stock part and its markings are visible, at least in my unit, so it was fairly easy to pull the firmware ROM and dump out the code - the CPU is a G65SC802, basically a 6502 but with some improvements. Studying it taught me enough to put a small videogame in the user-supplied ROM. (A friend of mine, on seeing that, started asking me when he was going to see NetBSD/tvi955 running on it. :) I also pulled the character-generator ROM and replaced it with flying leads to a solderless breadboard where I surrounded a RAM chip with logic so I could steal it from character generator duty to write to it. Accesses to it were fast enough that the flying leads introduced a lot of read errors, and stealing it for writes introduced more, but for character-generator duties read errors are relatively tolerable; they just produce snow on the screen. And it gave me downloadable character bitmaps, which was a fun hack. (When the character being downloaded is visible on the screen, it's particularly neat to watch the download happen, with all those glyphs changing as it proceeds.) I eventually replaced the ROM so as to give it a proper 8859-1 character set rather than the kinda-sorta-almost-8859-1 it came with. In any case, the main reason I'm writing is to offer to scan the manual if that would help. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B