Store the PC at address X and jump to X + 1.
Put all zeros in AC.
Add indirect: Go to address X. Use the value at X
as the actual address of the data
operand to add to AC.
Jump indirect: Go to address X. Use the value at X
as the actual address of the location to
jump to.
Load indirect: Go to address X. Use the value at
X as the actual address of the operand to
load into the AC.
Store indirect: Go to address X. Use the value at
X as the destination address for storing
the value in the accumulator.