Chapter – 1 Introduction
Computer Organization and Architecture
- Computer Architecture refers to those attributes of a system that have a direct impact on the logical execution of a program. Examples:
o the instruction set
o the number of bits used to represent various data types o I/O mechanisms
o memory addressing techniques
- Computer Organization refers to the operational units and their interconnections that realize the architectural specifications. Examples are things that are transparent to the programmer:
o control signals
o interfaces between computer and peripherals o the memory technology being used
- So, for example, the fact that a multiply instruction is available is a computer architecture issue. How that multiply is implemented is a computer organization issue.
- Architecture is those attributes visible to the programmer
o Instruction set, number of bits used for data representation, I/O mechanisms,
o e.g. Is there a multiply instruction?
- Organization is how features are implemented
o Control signals, interfaces, memory technology.
o e.g. Is there a hardware multiply unit or is it done by repeated addition?
- All Intel x86 family share the same basic architecture
- The IBM System/370 family share the same basic architecture
- This gives code compatibility
o At least backwards
- Organization differs between different versions