Successive approximation conversion
The "Test Value" is the "Current value" from the previous row OR'd with the "Test bit" from the current row.

The "DAC output" is the "Test Value" converted to a range of 0 to +5V.

$$\text{DAC Output} = 5V \frac{\text{Test Value}}{256}$$

And finally, if the output of the comparator is 1 (unknown input > DAC Output), then the "Test Value" becomes the new "Current value".