The system unit of a computer system
System Unit
Peripherals
storage peripheral
communication peripheral
output peripheral
input peripheral
mouse
microphone
keyboard
speaker
printer
USB flash drive
broadband modem
components
connected by
system bus
address buses
control buses
data buses
Display card
hard disk
Power supply
DVD-ROM drive
motherboard
floppy disk drive
Memory
CPU
Transfer data and instructions.
Transfer the source address or the destination address of data.
Indicate the direction of the data transfer and coordinate the
timing of the event during transfer.
main memroy
Cache memory
Random Access Memory (RAM)
Read-only memory (ROM)
functions
with attributes
executes machine cycle
contains
word length
clock rate
sub-cycles
execute
decode
interrupt
fetch
registers
control unit (CU)
Arithmetic and logic unit (ALU)
control register (CR)
General purpose register (GPR)
Use registers to hold data during calculations
Results are usually stored in a register called an accumulator
Perform arithmetic and logical operations
Keep track of the sequence of instructions being processed
Monitors and coordinates all I/O operations and system units
functions
Provide storage space for ALU and CU.
Fastest way for a CPU to access data
Memory units inside a CPU
types
Counter (CX)
Data register (DX)
Base register (BX)
Accumulator (AX)
functions
Load data from main memory into a register.
Store data temporarily in arithmetic operations.
Store data from a register into main memory.
functions
Contain the instructions to be executed by the CPUs
Contains the memory address of the next instruction to be executed
Facilitate the communication of the CPU with the main memory through the system bus.
types
Instruction Register (IR)
Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Status registers
Contain a number of flag bits indicating the status after the execution of instructions
Used in instructions of conditional testing and program branching
Read the next instruction from the main memory into instruction register (IR).
Identify the operation code and operands in an instruction.
Interpret the operation code and perform the required operation.
end of the execution of an instruction
Measure speed of CPU
Number of bits of data and instructions can handle at one time.
volatile
non-volatile
types
Erasable programmable read-only memory (EPROM)
Electrically erasable programmable read-only memory (EEPROM)
store the permanent information suppliesd by the manufacturer
contain the bootstrap program which loads and initializes the operation system of the computer
function
temporiy hold the data and instructions of application software and the operations system
types
Static Random Access Memory (SRAM)
Dynamic Randonm Access memory (DRAM)
high-speed memory
store data and instructions that have been recently used by the CPU
latest development of CPU and main momery
parallel processing of multiple cores
better pipeline technology
smaller chip die
high speed Double-Date Rate 3 (DDR3)SDRAM
shortern the speed gap between the CPU and main memory
operates a lower voltage level but higher frequency than its processsor