How are variables declared and used in Assembly Language?

In Assembly Language, variables are declared and used by defining memory locations to store data. These memory locations are typically referred to as variables or labels.

To declare a variable, we need to specify its name and the type of data it will store. This is done by using a label followed by a data directive. For example, to declare a variable named "count" that will store a 16-bit integer, we can use the following code:

count dw 0

Here, "dw" stands for "define word" and it allocates 2 bytes of memory for the variable "count" and initializes it with the value 0.

Once a variable is declared, it can be used in the program by referencing its label. For example, to increment the value of "count" by 1, we can use the following code:

mov ax, count
add ax, 1
mov count, ax

Here, we load the value of "count" into the AX register, add 1 to it, and then store the result back into the "count" variable.

Variables can also be used in arithmetic and logical operations, comparisons, and as operands for instructions. It is important to note that Assembly Language does not have built-in data types like high-level languages, so the programmer needs to ensure that the correct data size and type are used when working with variables.

Overall, variables in Assembly Language are declared by defining memory locations with labels and data directives, and they are used by referencing these labels in the program to store, retrieve, and manipulate data.