21 Oct
2008
21 Oct
'08
10:38 a.m.
In article <48FCDED4.60409 at axeside.co.uk>,
Philip Belben <philip at axeside.co.uk> writes:
The Tektronix 4052 and 4006 (and presumaby 4051 and 4012) do this.
These machines all have storage-tube vector displays, but when you want
to display text, scan a little dot matrix of the character. [...]
In all of these machines they do *not* send characters to the monitor.
They send dots or vectors. Just like in any character based terminal,
there is a circuit that takes a character and turns it into a pixel or
vector representation and *that* is sent to the monitor. Monitors
don't eat characters as input. Even an LCD display does not eat
characters directly, there is always something before it that turns a
character into a dot or segment pattern.
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They actually scan to the upper left corner of each
character, then
sweep out the 5x7 dot matrix for that character, before adjusting the
x,y deflection to the upper left corner of the next character.
I seem to recall the DEC VT11 (and thus GT40) did something similar. When
it displayed a character it scanned a little raster at the appropriate
place on the screen and used a normal dot-matrix character generator to
turn the beam on and off.