The Von Neumann Model

Functional Units
ALU = Arithmetic and Logic Unit
could have many functional units. some of them special-purpose (multiply, square root, …)
LC-3 performs ADD, AND, NOT
Small, temporary storage
Operands and results of functional units
LC-3 has eight registers (R0, …, R7), each 16 bits wide
Word Size
number of bits normally processed by ALU in one instruction
also width of registers
LC-3 is 16 bits