Yeah, though this feels artificially slow to me. Even the earliest Teletype machines could manage 10+ cps, and by the mid-70's time frame (v6 was released in 1975) much faster devices were available (and of course video terminals were starting to arrive too).
I'm sure someone used a PDP-11 with a terminal this slow, but it's unlikely to have been the typical developer experience.
I used a PDP-11/70 with ASR-33 TTYs as late as 1978. They were still common because while slow and noisy they were much cheaper than the DECwriter, and could also read and punch paper tape. Since mass storage was very expensive (10MB for $20,000) and since floppies were not yet common, paper tape was the USB stick of the time.
You, too? My high school had an 11/34 back in the day, with a couple VT100s, several Visual 200 terminals (cheap junk), one DECwriter II for the console, and another one plus a DECwriter III in the lab. It also ran RSTS/E, and in the summer after my sophomore year they offered a short introductory course. I was hooked. We didn't have any Fortran courses, though, just BASIC+ and COBOL.
I'd take even a DECwriter II over a Teletype, but the III made the II look downright slow, with a 4x faster printhead, the ability to seek quickly, and the ability to print in both directions to avoid wasted motion.
The point where I burst into giggles was when I realized that scrolling the page while output was still going (e.g. from ls /bin) overwrote previous lines with new letters.
That's some dedication to accuracy that's found there.
The Selectric didn't really do rollover, but it had a mechanism that felt like it. Each key lever had a small tab that entered a trough of ball bearings that had just enough slack for one tab. If you pressed a second key, it would displace the balls and descend when the previous key withdrew.
The teletype keyboard mechanism was less sophisticated than a Selectric. Also, I seem to remember it took like a pound of pressure just to push a key on a teletype, so you ended up vigorously punching it with your index fingers. A Selectric is like typing on air compared to a teletype.
Backspace had been invented; the problem is that on a printing terminal you end up with an illegible mess. So early Unix defaulted to erase '#' kill '@'. You can still see artifacts of that choice — ‘#’ being popular for things that start a line, like comments and C preprocessor commands, and ‘@’ being the only ASCII punctuation with no function in any common Unix tool.
