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Wow that was a pretty cool video. I have a lot of respect and admiration for the guys and gals who worked on these things back in the day. But I am lost on th

• kragen 11y ago
  You need one byte for the colors (4 bits to specify each of foreground and background) and 8 bytes for the on/off; if you have 1000 cells, then you need 9000 bytes in total. Another common thing to do, especially on machines just a little bit earlier, was to use one byte for the colors, one byte for a glyph identifier, and then put the 8 bytes per glyph somewhere else, maybe ROM, which was way cheaper than RAM. You could only have 256 distinct glyphs on the screen at a time, and maybe you couldn't even reprogram them, but you could do quite a bit of useful graphics inside those constraints. Text especially, obviously. And you could do it with a lot less memory. Nonprogrammable fonts were mostly just idiocy, because a quad-input NAND gate would have been sufficient to distinguish a 16-glyph RAM area from the ROM, and 128 bytes of RAM would have been sufficient for 16 8×8 glyphs; also, 5×8 glyphs were actually pretty common at the time. In the VT-52 and ADM-3A era, you had a good excuse; by the time of the VT-100 and H-19, it was just dumb. For better or worse, the less-idiotic Apple and Commodore mostly swept those pointlessly-crippled devices aside.