The large model supports up to 2 Mbytes of program and data space. The two programming models are almost identical. They differ only in the instructions used for branching and program flow control. Stacks A stack is a one-dimensional data structure. The stack consists of a block of memory, and a variable called the stack pointer.
Stacks are important data structures in both systems and applications programming.
They are used to store status information during subroutine calls and interrupt servicing. In addition, algorithms for expression evaluation in compilers and interpreters use stacks to store intermediate results. The processor uses the interrupt stack to save and restore the program state during the handling of an exception condition. This information is automatically pushed, by the hardware, on to the interrupt stack before entering an exception service procedure. On exit from the exception service procedure, the hardware pops this information from the interrupt stack.