[Coco] CoCo's TIMER and 60hz
dave at davebiz.com
Thu May 30 18:36:07 EDT 2019
But as Gene said, maintaining the accuracy of the device that’s in the cartridge would be the problem. I like his idea of tuning to WWV at 10 MHz though but I don’t think anyone a) cares enough about the issue, b) would spend the time and money to design it.
In reality, one of the more accurate timebases is the 60 Hz AC that is in your house. The utilities keep it pretty much dead on. I’m assuming one of the reasons for this is that in years past most clocks were mechanical and used synchronous motors. It’s too bad that the CoCo didn’t have a simple circuit to count the zero crossings on the AC. It would have kept a more accurate soft clock than most crystal-based oscillators.
> On May 30, 2019, at 4:32 PM, Brock Harrison <brock.erific at gmail.com> wrote:
>> On Thu, May 30, 2019 at 2:17 PM Gene Heskett <gheskett at shentel.net> wrote:
>> On Thursday 30 May 2019 02:33:17 pm Brock Harrison wrote:
>> Maintaining the accuracy of such a gizmo to generate real data as its
>> shipped around would be iffy, probaby best if it contained an SDR chip
>> so it could be twiddled to match wwv at 10 mhz. Then all the user would
>> need is a nylon rweeker and 20 feet of antenna wire, the higher the
> Perhaps my explanation created confusion. I propose a set of cartridge
> devices each containing a CPU tied to a time source that can be precisely
> measured and calibrated at a single location. The devices would each
> contain a small display (LCD or similar) that would present the noted
> frequency. Given the limited number of devices, CoCo owners could perform
> the tests with the device and then simply give the unit to someone else as
> folks meet or otherwise congregate. The device would include a web site
> URL utilized for resulting data entry.
> The exercise may be somewhat academic, but perhaps provide useful data
> concerning age of device versus drift, differences between various models,
> regional locations, etc.
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