Indirect Addressing Mode

6-14

Table 6–3. Field Bits and Notation for Indirect Addressing

Instruction Opcode Bits

15 8 7 6 5 4 3 2 1 0 Operand(s) Operation

8 MSBs 10000NAR*No manipulation of current AR
8 MSBs 10001NAR*,AR
n
NAR ARP
8 MSBs 10010NAR*– current AR – 1 current AR
8 MSBs 10011NAR*–,AR
n
current AR – 1 current AR
NAR ARP
8 MSBs 10100NAR*+ current AR + 1 current AR
8 MSBs 10101NAR*+,AR
n
current AR + 1 current AR
NAR ARP
8 MSBs 11000NAR*BR0– current AR –
rc
AR0 current AR †
8 MSBs 11001NAR*BR0–,AR
n
current AR –
rc
AR0 current AR
NAR ARP
8 MSBs 11010NAR*0– current AR – AR0 current AR
8 MSBs 11011NAR*0–,AR
n
current AR – AR0 current AR
NAR ARP
8 MSBs 11100NAR*0+ current AR + AR0 current AR
8 MSBs 11101NAR*0+,AR
n
current AR + AR0 current AR
NAR ARP
8 MSBs 11110NAR*BR0+ current AR +
rc
AR0 current AR †
8 MSBs 11111NAR*BR0+,AR
n
current AR +
rc
AR0 current AR
NAR ARP
Bit-reversed addressing mode
Legend:
rc
Reverse carry propagation
NAR Next AR
n
0, 1, 2, ..., or 7
8 MSBs Eight bits determined by instruction type and (sometimes) shift information
Is loaded into