4 ms·
Note CRTs where a luxury item in the early 1970s. A 5x7x64 character generator requires 2240 bits uncompressed. Perhaps get closer to 1K if you had some run len
by peter303 7y ago
Note CRTs where a luxury item in the early 1970s. A 5x7x64 character generator requires 2240 bits uncompressed. Perhaps get closer to 1K if you had some run length compression. In my 1975 MIT digital lab the 1K memory chips where kept locked up because they were the most expensive chips at that time. By 1977 a lab I worked in bought a CRT terminal for each student because character ROMs had dropped in price.
- gerbilly 7y agoBy 1985 the prices must have really dropped because the character encoder on my Apple ][e clone was actually an eprom that contained multiple copies of the bitmaps. It had extra address lines that weren't even used. Same thing for the keyboard encoder, IIRC.
- aap_ 7y agoThe characters are not actually stored as rasters though. There are up,down,left,right,intensify and end signals that control the beam and the logic and no more than 30 pulses per character. In fact, I took photos of the "ROM" earlier this year: https://imgur.com/a/QnFFkg6 https://imgur.com/a/QnFFkg6
- ncmncm 7y agoWe used to replace the character generator ROMs in Z19 terminals with our own that had two-pixel-wide verticals. It made all the difference.