5 Apr
2006
5 Apr
'06
1:51 a.m.
Don Y wrote:
...
So, you have to capture the incoming coordinates, solve the
difference equations to map the hyperbolae onto a spherical
globe, compensate for the *oblateness* of that globe, do
a 2D mercator projection, scale it to the desired user's
scale and then drive X & Y motors to move the pen from
where you were (last update) to where you *are* (in a straight
line, of course) -- without running off the edge of the page,
etc.
In addition to driving the multiplexed displays, scanning the
keyboard (debouncing keys, etc.), interacting with the user, etc.
Nowadays, I could code the whole thing in a month or so.
But, it sure wouldn't fit in that hardware footprint!
(keep in mind, 2Kx8 EPROMs were $50 at the time... $250 just
to store the code!)
...
--don
It sounds like you programmed a receiver some time ago.. I don't have the
manuf./model at hand but I know of a loran receiver with blue front panel,
lots of incandescent 7-seg displays, I think it was an 8080 CPU inside - sound familiar?
Is loran off the air now or is it still hanging on? It might be fun to connect
up an antenna and see if the above still works.