#D2S%DDATHD21@WISCVM.WISC.EDU (03/26/86)
From: #D2S%DDATHD21.BITNET@WISCVM.WISC.EDU
***********************************************************************
Hello netpeople,
It's some time ago, that <CB> found out, that the AMIGA clock is too
slow. We found out, that it is 10 Hz too slow. People at Amiga (or was
it Commodore ?) thought, it would be less expensive to use the AC-frq
as the CIA's real time clock. OK, it works (not very precise, but it
works - works with US-60 Hz.
In 'good ole Germany' we have 50 Hz, which is 10 Hz less. Trying to
change the 50/60 Hz-Bit in 68000 failed. Does the workbench clock set
the CIA's TOD to 60 Hz or did I something wrong ?
Anyway, It would be a great help, if someone of you could tell us how
to make that clock run at the richt speed.
so long Kosta
BITNET: #D2S@DDATHD21 < Show me Your disclaimer and >
ARPA : #D2S%DDATHD21 at wiscvm.wisc.edu < I tell You who You are... >
<CB>'s std. disclaimer!
***********************************************************************neil@amiga.UUCP (Neil Katin) (03/30/86)
In article <1635@caip.RUTGERS.EDU> #D2S%DDATHD21@WISCVM.WISC.EDU writes: >It's some time ago, that <CB> found out, that the AMIGA clock is too >slow. We found out, that it is 10 Hz too slow. People at Amiga (or was >it Commodore ?) thought, it would be less expensive to use the AC-frq >as the CIA's real time clock. OK, it works (not very precise, but it >works - works with US-60 Hz. >In 'good ole Germany' we have 50 Hz, which is 10 Hz less. Trying to >change the 50/60 Hz-Bit in 68000 failed. Does the workbench clock set >the CIA's TOD to 60 Hz or did I something wrong ? >Anyway, It would be a great help, if someone of you could tell us how >to make that clock run at the richt speed. > > so long Kosta > >BITNET: #D2S@DDATHD21 < Show me Your disclaimer and > >ARPA : #D2S%DDATHD21 at wiscvm.wisc.edu < I tell You who You are... > > <CB>'s std. disclaimer! Sigh. Your clock is not too slow, your software is too old. The 1.2 software dynamically figures out your line frequency and sets the appropriate constants for the timer. The reason why we used AC line frequency is because, over long periods of time, it is MORE precise. In the US it is guaranteed to be stable to a few parts in a million over 24 hours. We were told that the same was true in Europe. Other periodic timers (such as vertical blank) may vary up to 2%. The current timer is good to 5 seconds a day. Thats equivalent to .005%. In Europe, 1.2 prereleases are available from Gail Wellington, Commodore Electronics, Maidenhead UK. The phone number is 44-628-757-12. In the US prereleases are available to all registered developers through the normal support channels. If you have trouble getting it, let us at Commodore-Amiga know and we will do what we can to get it straightened out. Neil Katin pyramid!amiga!neil
daveh@cbmvax.UUCP (03/31/86)
In article <1635@caip.RUTGERS.EDU> #D2S%DDATHD21@WISCVM.WISC.EDU writes: >People at Amiga (or was it Commodore ?) thought, it would be less >expensive to use the AC-frq as the CIA's real time clock. OK, it works >(not very precise, but it works - works with US-60 Hz. I'm not sure how they do it with German 50Hz, but here in the USA all 60Hz lines are regulated. Just about any clock that plugs into the wall uses the 60Hz signal as its timebase. They actually change the frequency occasionally to insure that all the clocks using this featue will stay in time. Over long periods (if you keep you Amiga on all the time, in other words) the 60Hz pulse from the AC line will be FAR more accurate than any crystal clock. -Dave Haynie daveh@cbmvax.UUCP