Memory reference instructions are those commands or instructions which are in the custom to generate a reference to the memory and approval to a program to have an approach to the commanded information and that states as to from where the data is cache continually. These instructions are known as Memory Reference Instructions.
There are seven memory reference instructions which are as follows &
The AND instruction implements the AND logic operation on the bit collection from the register and the memory word that is determined by the effective address. The result of this operation is moved back to the register.
The ADD instruction adds the content of the memory word that is denoted by the effective address to the value of the register.
The LDA instruction shares the memory word denoted by the effective address to the register.
STA saves the content of the register into the memory word that is defined by the effective address. The output is next used to the common bus and the data input is linked to the bus. It needed only one micro-operation.
The Branch Unconditionally (BUN) instruction can send the instruction that is determined by the effective address. They understand that the address of the next instruction to be performed is held by the PC and it should be incremented by one to receive the address of the next instruction in the sequence. If the control needs to implement multiple instructions that are not next in the sequence, it can execute the BUN instruction.
BSA stands for Branch and Save return Address. These instructions can branch a part of the program (known as subroutine or procedure). When this instruction is performed, BSA will store the address of the next instruction from the PC into a memory location that is determined by the effective address.
The Increment if Zero (ISZ) instruction increments the word determined by effective address. If the incremented cost is zero, thus PC is incremented by 1. A negative value is saved in the memory word through the programmer. It can influence the zero value after getting incremented repeatedly. Thus, the PC is incremented and the next instruction is skipped.