> On Jun 23, 2016, at 11:28 PM, James Vess <theevilapple...@gmail.com> wrote:
>
> Hey guys,
>
> I was looking and found that the Tektronix 4010 is a calligraphic display,
> for which I found a video!
> https://www.youtube.com/watch?v=IztxeoHhoyM
>
> Let me know if it bares a resemblance to the display on the 6600
None, unless you count the fact that both are green and both use electrons.
The Tek 401x series displays are terminals (connected by a serial port). They
use storage CRT technology to create a persistent image (no refresh). They do
dot matrix ASCII text, line drawing, and have a crosshair cursor for input.
They use ASCII based text communication, at 9600 baud (I think they go that
high). The 4010 is rather a small tube, 24x80 characters; some other models
are much larger and can do quite impressive graphics at fairly moderate cost by
the standards of the time (mid 1970s).
The CDC 6000 series console (Data Display Co. DD60) showed up about 10 years
earlier. It's essentially a dual oscilloscope with X/Y input -- like typical
oscilloscopes it uses electrostatic deflection. The display itself accepts 9
bit X and Y coordinates, plus analog X/Y offset signals that are used to
produce the character outlines, a size selection signal (small/medium/large)
and a left or right intensify signal. The X/Y deflection signals are applied
to both tubes, but the intensify signal controls which of the two lights up.
In theory you could light up both simultaneously; the CDC controllers would not
do that. There's also a keyboard, with a 6 bit data signal plus key up/down
signals.
The 6612 or 6602 controller ("synchronizer" in 6000 terminology) connects a
6000 I/O channel to the DD60 (or, for some models, to a pair of DD60s). It
interprets commands to produce the X/Y position signals, advances X after each
character, and converts character data into the X/Y offset waveforms. The
waveform generator is essentially a counter feeding a ROM which feeds a set of
D/A converters. In the 170 series, it was done that way, but in the 6000
series display controller, the waveform generation uses a large complex
collection of gates instead of a ROM. Why, I'm not sure. A possible answer is
that a sufficiently fast ROM (100 ns lookup time) wasn't available in the early
1960s. The controller, when in keyboard input mode, would read the keyboard
lines and deliver the data (or 0 meaning no key down) to the PPU. No rollover,
which meant that typing fast required some practice.
Since the DD60/6612 hardware had no refresh machinery at all, the driving
software would do the refreshing. This made the display very dynamic. By
contrast, a Tex 401x is a storage tube, which puts it at the other extreme:
once you draw a character or line, it would stay without any further action.
You can't erase it; the only erase available is a full screen erase.
paul
