MOOG model D136-001-008 Product Description System Program Memory-it stores system working programs (monitoring programs), modular application function subroutines, command interpretation, call management programs of function subroutines and system parameters * which cannot be directly accessed by users. User program memory-it stores user programs. That is, the user program input by the user through the programmer. Function memory (data area)-The storage capacity of the user memory of the PC storing user data is usually expressed in words (16 bits/word). Note: the system program is directly related to the performance of the PC and cannot be accessed directly by the user. Therefore, the memory form, storage mode and capacity usually referred to in the PC product data refer to the user program memory.