ac@utcs.UUCP (12/15/86)
Some time ago I posted the following to net.micro.6809. Soon afterward the newsgroup disappeared. Since I got only one response to my posting I thought I might try again, this time to comp.sys.m6809. ---------------------------------------------------------------------------- Subject: COCO 3 clock speed 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 ------------------------------------------------------------------------- Subject: COCO 3 Basic bug? I have noticed an odd problem/feature of the print command. If you use a comma to specify column printing it doesn't work right for 40 or 80 column screens. For example try: FOR I=1 to 1000 PRINT I,I NEXT I For the 32 column screen I get 2 columns. If I specify WIDTH 40 or WIDTH 80 then the rightmost column shifts over one column to the right every time the number of digits needed to print I increases. Bug?? -- Name: Mark Acfield (University of Toronto Computing Services) Path: ihmp4!utcs!ac Alias: ac@utoronto.bitnet
dibble@rochester.ARPA (Peter C. Dibble) (12/23/86)
In article <1986Dec15.155154.14868@utcs.uucp>, ac@utcs.uucp (Mark Acfield) writes: > > Subject: COCO 3 clock speed > ... paraphrased "I suspect that the CoCo3 has an inaccurate occilator." > 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. > ... > 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 What's the ' in the basic program. Is the idea to see whether the program beeps in 999 seconds? I checked the accuracy of the CoCo 3's clock with the date t command in OS-9. It was losing less than half a second per minute. Since you found that several CoCo's were losing 2 sec per min in Basic and I got a different figure under OS-9, I'd guess that the problem is in software. Given that the CoCo3 has a countdown timer, that sounds like a good guess. See page 221 of the Tandy manual for the CoCo 3 where it says that TIMER returns a number that is incremented ROUGHLY every 60th of a second. Peter Dibble