Computer Organization and Architecture Tutorial 2 Kenneth Lee

One instruction has 20 bits 8 bits for operation code (opcode) 12 bits for the address of operand

Binary, Octal, Decimal, Hexadecimal Binary: Base two Only 2 numbers: 0, 1 0+1=1; 1+1=10 Octal: Base eight 8 numbers: 0, 1, 2, 3, 4, 5, 6, 7 1+2=3; 7+1=10 Decimal: Base ten 9 numbers: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 1+2=3; 9+1=10

Hexadecimal Base sixteen 16 numbers: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F 1+2=3; 9+1=A; E+1=F; F+1=10

2.2.a Load M(2) (Load the contents of memory address 2 to accumulator )

2.2.b Fetch: access the memory to fetch the instruction Execute: access the memory address 2 to load the data

This program will store the absolute value of the contents of memory address 0FA into memory address 0FB

Text book: p 53

(Text book p 56)

Text book p 64

Memory to processor Processor to memory I/O to processor Processor to I/O I/O to or from memory (Text book p 67-68)

Reduces propagation delay because each bus can be shorter Reduces bottleneck effects (Text book p 70-71)

MAR (Memory address register)  Specifies the address in the memory for the next read or write MBR (Memory buffer register)  Contains the data to be written into memory or receives the data read from memory Two registers used most frequently  All memory address related operation need go through MAR  All data transfer related operation need go through MBR

12 bit address 16 bit memory

16 bit bus 16 bit instruction

Ps. a 16-bit bus need one cycle to transfer a 8-bit instruction