Trying to get to grips with the DAC-08
The DAC08 also won't work properly without a negative supply voltage, in addition to the above mentioned problem.  The '08 output sinks current, so ideally it should drive a transimpedance amplifier, which you can make by connecting IOUT to the inverting input, noninverting to ground, and a gain resistor between the output and the inverting input. The output voltage will then be IOUT*R, where IOUT is set by the reference current and the binary input as described in the datasheet. If the output op amp being used in a transimpedance configuration isn't going to share the negative supply, it needs to have a common mode input voltage range that includes ground.