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Old 9th Apr 2019, 11:57 pm   #38
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: MK14 programming interface - MK2

Just when it didn't seem possible to be having more fun than we already are, I had another thought about this: What if the whole machine is running slow for some reason? Incredibly unlikely I know, but...

Try entering the code below (run it from 0F12). On my machine with its 4.43MHz crystal, Flag 0 generates a rock steady square(ish) waveform whose frequency is within one Hertz of a nice round-number audio frequency according to the 'frequency meter' on my Fluke 83 DMM.

What frequency do you get out of Flag 0 if you run it on yours?

Code:
0F12 C4
0F13 11
0F14 8F
0F15 02
0F16 C4
0F17 01
0F18 07
0F19 08
0F1A C4
0F1B 11
0F1C 8F
0F1D 02
0F1E C4
0F1F 00
0F20 07
0F21 90
0F22 EF
(...Why not just measure the frequency on the CPU oscillator pins?)

It's highly likely that the crystal is running at the right frequency, but also just possible that something else - induced noise?- might be halting the CPU for x% of the mains cycle (just for example). You can rule it out by trying that simple frequency generation test to see if your machine executes code at the same speed as mine.
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