Hi

I wonder if anyone could adivse me. I made a PIC16F84 circuit using all 13
I/O pins to drive 13 LEDs, but the LED connected to RA4 doesn't light up. It
appears that the pin does provide a signal, though. When I read up some more
in the PIC16F84 datasheet, I came accross a paragraph which said that all RA
pins are CMOS drivers, except RA4 which is an "open-drain" output. Is this
why it can't deliver current? What does the "open-drain" mean?

Thanks

Werner Soekoe
wsoekoe@global.co.za