adc0809 connected to parallel port

[montego]

Dear Sir

I am trying to build the ADC0809 circuit in you book Parallel port complete. I only read a value of Fff for each channel. Do yo have any suggestions of what the problem may be ?

The input is 0-5V to pin 1.
My PC system is a Pentium Dual core, using VB2005

I have used your original program and imported it into VB2005.

Could the speed of the PC system play any influence ?

If I change the program just to read one channelnumber, for instance channel 1, only channel 1 give a value of Fff. The other 7 channels show 0.

Thanks for you feedback.

[Jan Axelson]

To isolate the problem, use a voltmeter or 'scope to monitor the voltages on the pins. Use single-stepping to step through the program.