14.3xxx MHz signal on the ISA bus (was Re: Help identifying a
ard at p850ug1.demon.co.uk
Sat Jul 21 15:51:21 CDT 2007
> On 7/20/07, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> > 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
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...
> 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
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