Parport Outputbits high under Win 3.1


Thread Starter

Gert Love

I made the Parport interface from McComb's Robot Buider's Bonanza. I hooked it up to an old 386 with DOS and Win 3.1 installed.

I made a test program in Delphi 1 to write some output. LEDs are attached to check.

The funny thing is that bit 0 and bit 6 keep lighting up. If I send a byte that puts them up and then one that puts them low, they blink and get high again.

If I send a byte that puts the other bits high, they blink and go low again, even if I don't send a byte to put them low.

Can anyone explain this? Is this due to Windows 3.1? And is there a way to get around this?

I also tried it with test programs available on the web. With the same result. So I know it is not my code that is doing it...

Thanks in advance,