Re: TECH: AppleColor RGB Sync frequencies and dots sent Question

[david@uow.edu.au (David Wilson)]

Rubywand <rubywand@swbell.net> writes:
>     Right; which brings up another question: Including the left and
>right borders, how many dots are actually sent per line in 320 and 640
>modes?

Well, in the older Apple // modes, 65 characters are sent to display 40
so the overhead is 63%. Thus a in 640x200 mode there are probably about 1040
pixels including the overscan area and the horizontal refresh time.

This actually seems too high... My old OSI Superboard put out 32x32 characters
with no guard bands and was able to display 24 to 25 characters per line
and about 27 lines. 32/24 is only 33% extra. That would make it about 850
pixels.

Divide the above numbers by two for 320 pixel modes.

If you know the dot rate you can calculate the pixel count from the fact that
an NTSC 60Hz picture has about 65us per scan line (PAL 50Hz has 64us).
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia  david@uow.edu.au