This page describes the following instruction:
- Group: PAIR
- Mnemonic: pa
- Opcode: 249d, F9h
- Encoding: 1_111_1001b (PAIR_SRC_DST)
- Pseudo-code: if (o+pir)>255 then d+=1; pc++
- P:PARALLEL A:ADD
- Source is the Parallel Input register (PIR).
- Add source to O. If this produces a carry bit, add the carry bit to D.
The 'P' source is a data byte received on the parallel bus. See Device Communication for how this works. The 'A' destination takes the source value as the addend which is added to the Data pointer (register pair D:O). See In-Page Branching for more on this.