I'm not getting the same results. As I posted before, my results are:
Vpp checked -> pin 26 = -?
Vpp unchecked -> pin 26 = -?
Clock checked -> pin 27 = +5.8V
Clock unchecked -> pin 27 = +5.8V
Data (to PC) checked -> pin 28 = +3.6V
Data (to PC) unchecked -> pin 28 = +3.6V
I tried adjusting the COM settings in the BIOS and I activated COM2 which is actually a PCI modem slot on my motherboard. I also noticed that when I change from COM ports, when I go back to COM1, there is an error "Error in SetIntf(): Cannot open COM port". See screenshot below.
Incidentally, I also installed winpic800 and its giving me the same error of not being able to open my COM port.
I have the idea of building this simple programmer
http://www.foxdelta.com/products/art2003.htm to save me from more troubles. It has few components too, what do you think?