10 Feb
2011
10 Feb
'11
11:04 p.m.
The picture element measurement consists of the number of horizontal lines
multiplied by the horizontal resolution determined by the ability to
distinguish the transitions of a square wave as it increases in frequency.
Normally it was done by sweeping a square wave, increasing in frequency
along each line from left to right.
It's really a measure of video bandwidth. My last job as an engineer before
moving to DEC was designing character based VDU's.
Regards
?
Rod Smallwood
?
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Tony Duell
Sent: 10 February 2011 19:58
To: cctalk at classiccmp.org
Subject: Re: Tektronix 4010/4014 terminal printer project
In article <d7c81ea7b43ac08503dccfb4a518a78e at cs.ubc.ca>,
Brent Hilpert <hilpert at cs.ubc.ca> writes:
Actualy, I would say the 4631 printer is very close to being a TV system.
As I understnad it (and it's been some years since I looked at the
schematics), the printer casues an electron beam (from the flood gun?) to
be scanned over the storage target in a raster. This produces a signal
indicating the charge level on the target for that point. And the printer
has a 1-dimentinal CRT whic his sanned in synchronism to the raster
lines, its image is recorded o nthe apepr. The vertical 'deflection' in
the printer is obtained by advancing the paper.
No matter how the image in the storage tube is put there, the printer is
a raster devvice. There is a limited vertical resolution from the number
of lines in taht readout raster. I assume the horizontal resolution is
limited only by the bandwidth of the system.
-tony
On 2011 Feb 8, at 7:16 AM, Richard wrote:
Sure, but its not a TV system. There is some limit to the resolution
of a 463{1,2} printer. There is also some limit to the resolution of Philip Belben <philip at axeside.co.uk>
writes:
I know what you mean here, so not to argue your point about the analog
process in the system under discussion, but I would like to add an
historical footnote: even analog raster-scan systems were characterised
in terms of "picture elements" going back to the very early days of TV. For that matter, how big are the pixels?
There aren't any pixels.