Intel 8080 instruction... what is the etymology of the "DAD" instruction mnemonic?

3
votes

I am learning about the Intel 8080 processor in Charles Petzold's excellent book Code. The DAD instruction was explained as far as what it accomplishes, but I have a weird thing about alphabetical codes like this where I have to know what they stand for. For example ADC stand for ADd with Carry. Or SBB for SuBtract with Borrow.

But what about DAD? It's a silly question I know, but I'm wondering if anybody knows the answer. Google is yielding nothing...

4
assemblyinstructionsinstruction-setintel-8080

4 Answers

4
votes

DAD stand for D-ouble byte AD-d.

2
votes

Double precision ADd. For these instructions, HL functions as an accumulator. DAD B means BC + HL --> HL. DAD D means DE + HL -- HL.

1
votes

I guess it is simply Double [width] ADd. Its role of adding *D*ouble values is obvious:)

1
votes

DAD is a Double Byte Add instruction.