Final answer:
The provided program is a simple assembly language counter that starts with the value 10 in the AL register and counts down to 0 using a loop. The instructions used include MOV, DECB, JNZ, and HLT. DECB decreases the register value with each loop iteration and JNZ keeps looping until the zero flag is set.
Step-by-step explanation:
A counter in assembly language is a simple program that can be used to count down or up to a specified value. Below is an example code in assembly language that counts down from 10 to 0 and describes the instructions used:
MOV AL, 10 ; Initialize counter with 10
COUNTDOWN: ; Label for loop start
DECB ; Decrement the value in AL
JNZ COUNTDOWN ; Jump to COUNTDOWN label if zero flag is not set
HLT ; Halt the CPU (optional, depending on how you want to end the program)
Here is a brief description of the instructions used:
- MOV: This is used to move or load immediate data into a register. In this case, it sets the AL register to 10.
- DECB: This instruction decrements the value in a register by 1. Here it decrements the AL register, which is holding our counter.
- JNZ: Jump if Not Zero. This instruction is a conditional jump that takes us back to the beginning of the loop labeled 'COUNTDOWN' if the zero flag is not set, which happens when AL is not zero.
- HLT: This instruction halts the CPU. It is optional and often used to indicate that the program has finished executing in a controlled manner.