Kernel

For TI-89 Flash family assembly, a kernel is used underneath the shell. The kernel provides the actual access to assembly functions while the shell provides a menu system for the programs. Therefore the shell is not strictly required to run assembly, but the kernel is. Kernels and shells are not dependent on each other, they can be mixed and matched. (On other calculator models the kernel and shell are integrated into one file.) The term shell is often used to mean the combination of a shell and kernel. Nostub assembly programs do not require a kernel.