[Coco] CoCo 3 Serial Interrupt

tim lindner tlindner at macmess.org
Fri Oct 15 15:30:20 EDT 2010


Disappointing sigh.

It looks like someone put the space before their mark. Gotta love serial humor!

On 10/15/10, Darren A <mechacoco at gmail.com> wrote:
> On 10/15/10, tim lindner wrote:
>> I was reading Tepolt recently and it said the serial interrupt
>> occurred then the serial line when from low to high. Is this correct?
>>
>
> ---
>
> I've never tried it, but while looking at the CoCo 3 schematic some
> time ago, I noticed that as well.
>
> The serial input signal coming out of the SALT chip goes directly to
> the PIA and is also inverted by U15 before going to the active low
> interrupt pin on the GIME.  An interrupt should therefore be triggered
> on a transition from logical 0 to 1.  Seems kind of pointless since I
> would exepct an interrupt to occur on a start bit which is a
> transition from 1 to 0.
>
> Darren
>
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>


-- 
tim lindner



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