[Coco] Re: [Color Computer] Re: Interfacing question.

[Gene Heskett]

On Tuesday 22 March 2005 22:03, j_e_daggett wrote:
>--- In ColorComputer at yahoogroups.com, Gene Heskett
> <gene.heskett at v...>
>
>wrote:
>> Or switch to a 6309, which can cheerfully source or sink 20 ma per
>> pin, and its logic one outputs are the supply rail for all
>> practical purposes.
>>
>> [...]
>
>*******
>
>on a good day and if you hold your breath for a year.
>
>Not according to the Hitachi spec I have will the 6309 sink and
> source 20ma per pin. The max output current is 100ma and that is
> the sum total of all the address buss, databus and control signals.
> You run that current to long and I guarentee the part will get warm
> as nice bed bug.

Oh not much doubt there.  But the individual pin can do that if it has 
to.  The one I've spent quite a bit of time looking at with scope 
probes did go rail to rail quite nicely, this with a multipack full 
of cartridges plugged in, a disto SC2 4n1 in the back slot, a wp-rs 
in the next one, and 2 rs232 packs, one of them modded for two ports 
in the front two slots.  And it ran cool enough (on an external power 
supply, not that built in toaster the coco's have) that I can turn it 
on, boot up nitros9, bury it under a furniture blanket, come back and 
lift the blanket a day later to read the darkroom thermometer laying 
over the memory, and its 3 degrees above room temp.

Even on the more heavily loaded A0-A3 lines, both transitions were 
well under 10ns, the bandwidth limit of my 100 mhz dual trace hitachi 
V-1065 scope.  Its an amazing chip IMO.  I'd love to take one running 
exclusively on a WP-RS for its video i/o, and crank up the clock to 
see just how fast it could run.  With fast enough memory, I'd bet on 
20+ mhz.  Something else would fall over first.

>The 6309 has a VOH voltage than the 6809. Which would improve his
>problem. The 6809 is rated VSS+2.4 VDC min while the 6309 is rated
> 4.1 VDC min.

That, I'd venture to say, would be under a lot heavier load than the 
coco puts on it to pull it down that far.

>james
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Copyright 2005 by Maurice Eugene Heskett, all rights reserved.


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