21 Jul
2007
21 Jul
'07
1:51 p.m.
On 7/20/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Not that I know of. But it was used on quite a few cards you'd not
expect, just as a master clock. I know, for example, my POST card
(displayes the POST errror codes) divides OSC down by 2^n (for a large n)
to get the display multiplexing signal...
The OSC signal was the 14.3xxx MHz master clcok
signal in the PC and XT...
It was used, of course, by the CGA card as the master clock for the video
and colour cubcarrier timing. Some other cards used it, often divided
down, as a master clock.
Is there a list anywhere of what cards tended to use that signal? I ask because I manufacture the GG2 Bus+ bus adapter for
the Amiga, and,
because that signal is on the ISA bus, the designer of the card
slapped a $3 oscillator on it to provide it. I have a number of
unassembled cards and, honestly, would like to leave that signal off
if there's no expectation of folks needing it.
You seem to have a choice. Save $3 and have to put up with people
complaining (and even worse not complaining, but telling their friends
that your design doesn;t work right) or do things properly and fit that
oscillator.
-tony