3 Apr
2024
3 Apr
'24
3:26 p.m.
On Apr 3, 2024, at 11:16 AM, Paul Koning via cctalk
<cctalk(a)classiccmp.org> 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.
paul
On Apr 3, 2024, at 11:01 AM, Guy Fedorkow via
cctalk <cctalk(a)classiccmp.org> wrote:
Vintage computer enthusiasts might want to keep track of where to find CRT-based analog
oscilloscopes, for use as output devices.
The early MIT and Lincoln Labs computers used D/A converters to steer and activate the
beam on analog scopes to draw vector images.
Working on Whirlwind simulation, we've been able to get this technique to work with
"real" oscilloscopes, e.g., Tek 475, but we have not yet found a single DSO that
has X/Y _and_ Z inputs (let alone the required phosphor fade).
So did a whole range of DEC computers, of course. And the famous CDC mainframe console
(DD60) though it did vectors only for text (graphics was dot-mode only since it wasn't
a major use case for that device).