3 Apr
2024
3 Apr
'24
5:49 p.m.
Paul wrote:
The DD60 and its associated controller in the
mainframe (6612 or 6602) was an > interesting beast. The interface between controller
and display is a hybrid, > with the positioning information delivered as 9 bits each of
X and Y, but the > character vectors are generated in the controller and sent to the
display as
analog waveforms, X and Y on differential pairs.
Another oddity is the character waveform generation:
that uses two pairs of
A/D converters, and the converters are essentially base one -- 6 equally
weighted inputs to produce output values 0..6. And since ROMs were hard to
come by in 1964, at least ones with 100 ns cycle time, the digital inputs for > the
waveform generators are an amazingly large pile of gates.
I was a systems operator (as it was called back in the day) on a Control Data Cyber 73 at
Tektronix for a number of years. The round console displays on the machine were simply
beautiful. The characters were very clear and easy to read, even though they packed a lot
of them on the screen. One thing that I thought was particularly cool about it is that
you could pull up a page of any section of memory and watch the live data flicker around
as the machine was running. Pretty amazing.
On a similar display topic, I have a very unusual old electronic calculator made by a US
company called Wyle Laboratories. The machine was designed in the 1962-1063 timeframe.
It is all Germanium-Transistor and Resistor logic(RTL). The Model WS-01/WS-02 (two
versions, both using the same display subsystem, but varied in terms of the main register
storage) calculators used a CRT display for showing the content of the registers to the
user. The display
consists of six lines of 24 digits each. The six lines represent the content of three
memory registers, the accumulator, a multiplier-quotient register, and the numeric entry
register.
Even with only having to render the digits zero through nine and a decimal point (the
calculator didn't support negative numbers; they were represented using tens
complement form), the display generator also used a batch of diode-transistor gates to
generate the digits. The interesting thing about it is that instead of generating
strokes to create the digits, the machine uses sine/cosine waveforms that are gated by the
character generation logic to draw the digits on the screen. The position of the digits,
like the CDC scopes, is derived by precision resistor DACs, and then a mixer takes over as
the character is drawn using gated segments of the sine and cosine waveforms mixed
together with the position voltage. The result is really beautifully rendered digits
that look almost like they are drawn by a draftsperson who is extremely consistent in the
drawing of each digit. The CRT has yellow-orange phosphor with a moderate persistence, so
when the digits change, they look like they quickly morph from one digit to the next.
The digits are among the nicest looking digits that I've ever seen on a CRT display,
including those on the CDC scopes as well as IBM console displays.
They are far more aesthetically (to my taste, anyway) pleasing than the segmented digits
drawn on other CRT-display calculators such as the HP 9100A/B, Friden EC-130/132 and 116x,
Victor 3900 and 14-321/14-322, SCM Cogito 240/240SR, Busicom 202/207/2017, and some
calculators (usually clones of US or Japanese-designed machines) made in the former Soviet
Union.
-Rick