4 Apr
2024
4 Apr
'24
7:12 p.m.
On 2024Apr 4,, at 7:22 AM, Adrian Godwin via cctalk
<cctalk(a)classiccmp.org> wrote:
This 'scope clock also uses circle generators rather than vectors to
produce well-formed characters. It mentions a Teensy controller so I don't
think it's the original made in this way - the first I heard of was too
long ago for that. But I don't know if it's an update or a separate design.
https://scopeclock.com/
<https://scopeclock.com/>
Technically, the scopeClock is generating neither curves nor vectors, it's
generating pixels in an XY display - it's just that they’re of fine enough resolution
and fast enough that they’re seen as a smooth-enough curve on the CRT.
The MIT/Electronics-magazine and Wyle techniques are using analog electronics to generate
portions of sine waves for selected phase periods and phase relation such that when
applied to the XY cartesian display you get continuous portions (chords) of circles. Some
digital logic gates the analog sine generators appropriately to produce the chords and
line segments, with offsets, in a sequence to form characters.
The scopeClock, in contrast, is using DACs in the microcontroller to generate (discrete
approximations of) sine wave segments - which is to say it’s relying on the abilities of
inexpensive current-day high-speed digital electronics.
Thanks Paul, for pulling up the article, I recalled it as well when Rick mentioned the
technique of the Wyle. I think I ran across it many years ago when sorting through stacks
of Electronics magazines at our radio museum.