Can someone explain the mysterious non-behavior of the DAC0808 and DAC0832, is there a difference between them on the output side?
Strangely you've chosen a current (as in amps) output DAC (DAC0808) and, to get a voltage out you need an op-amp added to the output: -

Same story for the DAC0832: -

Both these devices are as old as the hills so you might want to choose something more modern and accurate. Maybe a voltage output DAC like this might suit: -

Try this link to Farnell - it's set up for 8 bit DACs with an 8 bit parallel port.