Re: Anybody with an oscilloscope as an Apple II display?

[Charlie Springer <RAM@regnirps.com>]

On Wed, 2 Apr 2008 14:32:07 -0700, Michael J. Mahon wrote
(in article <ba-dnWXeJ-XFZm7anZ2dnUVZ_hGdnZ2d@comcast.com>):

> Charlie Springer wrote:
>> On Tue, 1 Apr 2008 12:52:56 -0700, Michael J. Mahon wrote
>> (in article <07CdnQbALc4HD2_anZ2dnUVZ_oOnnZ2d@comcast.com>):
>> 
>> 
>>> Fun with scopes is probably what led me to interactive graphics
>>> as my first excursion into interactive computer programs (around
>>> 1964).  The graphical capabilities of the Apple II were one of
>>> its strongest attractions to me in 1980.
>> 
>> 
>> Micheal, you may not be aware, but Jef Raskin's thesis from 1967 is 
>> entitles 
>> "QuickDraw, A graphical computer interface". I think I have it right.
> 
> I've been curious about his thesis, but haven't yet found it.

I don't have a copy. There may be one in his papers in the Stanford archives 
or at, hmmm. UCSD?

> When the photomultiplier was pointed toward an operating TV, the
> video waveform was visible on the scope, and could be displayed
> (with some smearing) on another monitor.  This same approach, when
> used with a telescope, can be used to see what TV shows are on in
> nearby houses, even if the light from the screen is only indirect!

Cool. The smearing must have been from the decay of the phosphors. I think 
there is a typical half life of less than 1/60 second for TV. I analysed a 
bazillion tubes and phosphors for the Swyft project but can't remember the 
details. We didn't need them that fast and were after a paper white with no 
green ghosting when scrolling and such -- Swyft and Cat had black type on 
white background for WYSIWYG.

snip

> BTW, you may have been a little late for the light pen, since the
> first use of a light-sensitive device (a light "gun") that I know
> of was developed in the 1950s (using a photomultiplier) to designate
> targets on a computer-driven radar scope.  It was the SAGE system,
> running on IBM's AN/FSQ-7, IIRC.

Well, to be fair, the pen in that case would be a bit bulky without an 
optical fiber and have 600 to 1,200 volt supply. But I do remember some 
really neat half inch PMTs (Hamamatsu?). I suppose a plain old phototube 
would have worked fine as a light pen with a piece of lucite light guide or 
some such.

This is getting very retro. I want to find a nice inexpensive 7 to 12 inch 
LCD to use with my //e and //GS stuff. With a CFFA card inside and a nice 
tilt-up LCD it could be very convenient.

-- Charlie Springer