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∂19-MAR-76  0150	HPM  
Thanks for the note.
The ideas i briefly dumped on you a year ago have evolved much and
have become an obsession. Am in the process of writing up a synopsis,
to be complete by the end of the month, and you get a copy. Essential
idea is a moby (10↑3 to 10↑6 machines) multiprocessor interconnected
by Batcher sorting nets, which offer crossbar equivalence at n*(log(n))↑2
cost. Some programming languages (including LISP) and operating systems
for it vaguely defined, with some clear spots.
Yes I am interested in a copy of your text, if you can spare one. Knowing
my failings, though, I won't promise to generate many helpful comments.
∂20-Feb-78  1739	HPM  
 ∂14-Feb-78  0624	JRA  	video    
hi; been trying (obviously unsuccessfully) to call you here. 
i'd like to demo SUDS and your xgpsynthesizer to some  peope  from
HP labs. would you be  interested, available, etc for talking with them?
if so, when's good time for you (and channels 41-47!)
				john 
				494-1444 x323

sorry for not getting back to you sooner. I've been coming in late afternoons,
which is almost completely out of pahse with you. You don't really
need me to do the demos, do you? The channels are free in the mornings,
as you must be aware. With some warning, enough channels could
be guaranteed at 7 pm or so, also. Good luck on getting a terminal!
∂27-Feb-78  1706	HPM  	more video    
1. the xgp-to-gray sacle algorithm ( i know you told me once, but
    (blush, blush) i forgot.

2. given the gray scale channels, how much  smoothing does the 
    video synthesizer do.

*******
imagine a page of XGP output. It is 8 1/2 by 11 inches and has 200
dots per linear inch in each direction, each dot being black or white.
Call a black dot a 1 and a white spot a 0. The page is then an array
of 2200 rows and 1700 columns of bits.

Each data disc channel is conceptually organized into 480 rows and 512
columns of bits. There are 32 of these channels altogether, all producing
bits simultaneously.  Normally they are used to operate 32 different tv
screens, each a 480 by 512 by one bit display. Eight of these channels go
to a digital to analog converter. This D/A is thus provided with eight
bits for each of the 480x512 points on a TV screen. It takes these
8 bits and translates them to one of 2↑8 grey level values. Thus the
output of the D/A is a tv image with 480x512 samples, each one of 2↑8
shades of grey. The data-disc:D/A converter is called the video
synthesizer. There is no additional smoothing except perhaps that
caused by the limited frequency response of the video amplifiers
anlong the way to your TV screen, and by the finite spot size of
the electron beam in your CRT.

The XGP dot array is more than three times as wide the data disc
array, and more than four times as tall. Also, the TV screens are
wider than they are tall, making them just about right for displaying
a half page of XGP output. A half page is still over 3 times as wide
and 2 times as tall as the DD array. By throwing away some of the
(hopefully) blank border on the page, the ratios are made exactly
3 and 2. So now imagine that each DD dot must somehow represent
a little 3 by 2 subarray of the XGP array. If we sum up the number
of 1's in each of these subarrays, we get numbers from 0 to 6.
If 0 represents white and 6 represents black, with the numbers
in between representing proportional shades of grey, we can display
the resulting pattern on the video synthesizer. It looks like
a blurred version of the XGP page. That's half density XGPSYN.
Full density turns the page on its side and compresses the
page length by a factor of 4 (instead of 2) and the width by
3, as for half density. Double density does 4 lengthwise and
6 sideways (giving numbers from 0 through 24).

The simple summing over subrectangles is a filtering. Other
more complicated filtering algorithms, that involve shading some
adjacent dots, might give even better results [CACM V20 #11 799:805].
*******


3. where, oh where, might i find the video synthesizer details
    and even perhaps the xgp synthesizer listings?

*******
The source for XGPSYN is XGPSYN.SAI[PIX,HPM], though I don't think
it will be too helpful.
*******

these and other questions can only  be answered by YOU. 
besides, the gratitude of the huddled masses, I'd even autograph
a  copy of my forthcoming (and outgoing) LISP book.

*******
wow!
*******
					i await pregnantly,
					john