INEL 4215: Computer Architecture and Organization

Lecture notes, January 28, 2004

Lecture 5

Chapter 2: Machines, Machine Languages, and Digital Logic

2.1 Classification of Computers and their instructions

Classify according to main memory and CPU registers

Main memory – array of data units having the smallest size that is accessible using the machine instruction set. Almost always 8-bit-byte

CPU registers – Special purpose registers

Different sizes & types of data.

Example:

Classification according to structure and function of registers in CPU

1. Accumulator machines – limited number of data accumulators (usually one) and address registers within CPU.

accumulators → address of operand and result of operation are saved on the same accumulator register.

\ → Only one address was specified in opcode (1-address machines)

Old structure – very limited (what would happen if we try to solve arithmetic expressions with many terms)

Example: Motorola M6800 and Intel 8086.