The PDP-7 Where Unix Began

Re:The PDP-7 Where Unix Began by peter303 on Thursday October 10, 2019 @10:51AM (#21215157)

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.

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Re:The PDP-7 Where Unix Began by aap_ on Thursday October 10, 2019 @03:35PM (#21218354)

The 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

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Re:The PDP-7 Where Unix Began by gerbilly on Thursday October 10, 2019 @12:07PM (#21216140)

By 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.

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Re:The PDP-7 Where Unix Began by ncmncm on Friday October 11, 2019 @02:36PM (#21227103)

We used to replace the character generator ROMs in Z19 terminals with our own that had two-pixel-wide verticals. It made all the difference.

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