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1 total messages Started by ac Wed, 12 Nov 1986 19:53
COCO 3 clock speed
#825
Author: ac
Date: Wed, 12 Nov 1986 19:53
28 lines
2134 bytes
   When I got my new COCO 3 home all seemed fine except that the image it
produced on my TV screen was wavering somewhat.  I thought perhaps some
hum was coming from the power supply and took the machine back to the
store to compare it with another one.  As to be expected, when I got there
my machine performed flawlessly.  I even took it to a second store to
try it out there.  Again, the display seemed fine.  I was about to give up
and assume that some strange interaction between my TV and my COCO 3 was
occurring.  Thing was though, I also have a COCO and a COCO 2 and they
didn't exhibit this problem.  Then I remembered that home television use
a refresh rate of 60Hz so that any hum that might creep into the display
won't cause screen wavering.  Perhaps the COCO 3 clock was of frequency.
I decided to check this out using the TIMER function built into basic.
The result of my experiment, which by this time came as no surprise, was
COCO 3 counts of 60 seconds in about 58 seconds or real world time.
Again I went back to the store,  this time armed with my little timer
program.  To my suprise, their COCO 3 also took 58 seconds to count
of what should have been 60 seconds.  Next we tried 4 more COCO 3's.
All seemed to run fast.  Now this amounts to a 3% error.  Hard to
imagine that this is just slightly off crystal.  Perhaps all you who
have access to a COCO 3 could try checking them to see if they run fast.
My little timer program is listed below (as well as I can remember it):
10 TX=999
20 TIMER=0
30 '
40 T=INT(TIMER/60)
50 IF T<>TX THEN PRINT T:TX=T:SOUND 100,1
60 GOTO 30
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