On 2018-06-06 12:31 PM, Noel Chiappa via cctalk wrote: > > From: Toby Thain > > > It's suggested there (without any proof though) that the CDC used a > > Fourier process > > ... > > I'd be very interested to know what you find out about the circuitry. > > Someone very kindly pointed me at: > > > http://www.bitsavers.org/pdf/cdc/cyber/cyber_70/fieldEngr/60125000C_6602_6603_6622_6681_6682_Data_Channel_Diagrams_Dec65.pdf > > (although why it's in the Cyber70 folder, I'm not quite sure :-). I don't > completely understand it (it's only drawings, no text, and the notation is > unfamiliar), but I think I get the general drift - and it's pretty baroque! > > Very briefly, it appears to me that characters are generated from short > vector-type strokes placed in a 7x7 matrix, with each stroke being encoded as > motion of 0, 1 or 2 'boxes', both horizontally and vertically, from the 'box' > of the end of the previous stroke. A character can contain up to 22 strokes, > but most seem to average about dozen or so.
OK, so that's definitely not a Fourier technique. I admit I was sceptical of the tweet. :) Thanks for the link. > > The pronounced rounding which I noticed in the characters must be caused by > the limited bandpass of the A-D system, amplifiers, etc - it can't actually do > a sharp corner when going from e.g. a vertical stroke to a diagonal one. Or > something like that.. :-) Makes sense. --Toby > > Noel >
