How the real time clock interrupt
can screw up the timing of your EFI program.
ZBasic has a built in real time clock.
Not needed for EFI applications.

Here is a real simple test program for
setting  a bit low for a time and then
back high. Sort of a low cost function generator.

Public x as long

Sub Main()
Register.TIMSK2 = 0  'disable the real time clock.
for x = 1 to 90000000
Call PutPin(12, zxOutputLow) ' pin 12 will be at logic zero
Call PutPin(12, ZXOutputHigh)
next x
 End Sub

Here are the scope traces with and with out the
real time clock.

All you need do is turn it off once at the start
of your program  and it stays off.


Paul Lamar