[hatari-devel] TT mono mode Timer-C problem

["Roger Burrows" <rfburrows@xxxxxxxxx>]

I was testing EmuTOS using TT mono mode (TT High), and had problems opening a 
drive window by double-clicking on the desktop icon.  After a bit of work, I 
discovered that the 200Hz (5 msec) system timer is actually running at about 
400Hz, which (among other things), speeds up the timer interrupt at etv_timer, 
and causes double-clicks to seem twice as slow as they really are.

The attached program (compiled under Lattice C on a real TT) uses the system 
ticks value in low memory to count off seconds and display them.  If you run 
this in TT mono mode, the seconds go by at about twice the normal rate.  The 
program also uses a crude loop counter to see if there is any significant 
variability in the time between clock pulses (I wondered if perhaps two clock 
pulses were being signalled every 5msec), but there doesn't seem to be.

This problem occurs with either EmuTOS or TOS 3.06, but ONLY in TT mono mode.  
It does not occur if the screen mode is set to RGB.

Roger Burrows

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