With the Arduino, BS2, or Propeller chip the first thing I always do is get an LED blinking. From there it is usually a short trip to bit banging stepper motor control signals. So I finally got something working using ehBasic, an LED, and a 6522. The program below sets PB0 for output and toggles the LED on and off 16 times.

In EhBASIC only the first 2 letters of variables are significant. So Via2PRB and Via2DDRB are the same variable: Vi. You are toggling the VIA's DDRB register instead of the PRB register, because that is the last definition of Vi. Of course that still works, if the LED is between Vcc and the port pin. PRB defaults to $00 after a reset. The port pin will start sinking current when it is defined as output and go to high-Z when it is not.

But you are not alone. I made the very same mistake in my first EhBASIC program.

edit: You will find more errors in your little program, if you fix the variables.

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6502 sources on GitHub: https://github.com/Klaus2m5

Thanks for the feedback as that was exactly what I was looking for by posting this. I will fix that error and then find the others.

This is also an 80's flashback, that used to be common behavior among Pascal compilers, although I think it was six or eight characters that they considered significant. Used to drive me crazy.

After discovering the BITSET and BITCLR commands this got much easier.



I probably need a better way to wait than a delay loop. I've heard that 6522's have a one shot timer, so I'll need to see if that can help.

The 6522 has two timers with several operating modes, but by themselves they might not give as much delay as you want. The methods in my article at http://wilsonminesco.com/multitask/index.html on Simple methods for multitasking without a multitasking OS, for systems that lack the resources to implement a multitasking OS, or where hard realtime requirements would rule one out anyway, can be implemented even in a simple BASIC system. Then you can do other useful things while delaying, instead of wasting that processor time in a delay loop. The delays will be pretty accurate regardless of other things you have going at the same time.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?