Processor Components And Storage Devices Flashcards
CPU
Central Processing Unit (Processor) - made up of components and has pins made of gold
MAR
Memory Address Register - Holds the address in memory where processor is required to fetch/store data from/to
MDR
Memory Data Register - Temporarily holds data moving between processor and main memory
CIR
Current Instruction Register - Holds current instruction which is made of opcode and operand
Opcode
The part of the instruction that tells the processor what should be done
Operand
The part of the instruction that contains the data to be acted on, or the memory location of the data in a register
PC
Program counter - holds memory address of next instruction to be executed
Accumulator
Stores results from ALU
Several locations of super-fast memory called registers
Processor is able to access and reuse results in subsequent calculators
Memory Read
Causes data from addressed location in RAM to be placed on the data bus
Memory Write
Causes data on data bus to be written into addressed location on RAM
Bus Request
Indicates device is requesting use of data bus
Bus Grant
Indicates CPU has granted access to data bus
ALU
Arithmetic-Logic Unit
The problem-solving part of the processor
Arithmetic
Add, subtract, multiply, divide
Logical
and, or, not, xor
Shift
move bits to left/right within a register
Fetch execute cycle
Fetch -> Decode -> Execute -> Repeat
Buses (what are they?)
Series of connectors transferring signal between components
8, 16, 32 or 64 lines
System Buses (names)
Control
Address
Data
Info held by CPU (3)
Current instruction being executed
Address of data that it needs and also the data itself
Address of the next instruction to be executed
Clock
Synchronises operations
Control system (5)
Memory Read
Memory Write
Bus Request
Bus Grant
Clock
ALU operations
Logical
Arithmetic
Shift
System bus diagram
CPU <-> Control Bus
CPU -> Address Bus
CPU <-> Data Bus
Memory <-> Control Bus
Memory <- Address Bus
Memory <-> Data Bus
Input & output <-> Control Bus
Input & output <- Address Bus
Input & output <-> Data Bus
Dedicated Registers (5)
PC
MAR
MDR
CIR
Accumulator
RAM
Random Access Memory. A volatile form of high speed memory that can be quickly and easily read from and written to.
Control bus
Sends control signals to coordinate execution of instructions and controls fetch-execute cycles and buses
Address bus
Carries the memory location address of the register the data is being carried to or from
Data bus
bi-directional bus to carry data between processor and memory
Word
A unit of memory measuring 8, 16, 32 or 64 bits. Each word has a separate memory address
Clock speed
Pulses of the clock trigger the fetch execute cycle therefore faster clock = faster fetch execute cycle. Clock in a 4GHz processor pulses 4 million times a second
Dual core
2 processors linked together within an integrated circuit. Can theoretically process 2 instructions at once as each core has its own fetch execute cycle though instructions are usually sequential
Quad core
4 processors linked together within an integrated circuit. Can theoretically process 4 instructions at once as each core has its own fetch execute cycle though instructions are usually sequential
ROM
Read Only Memory. Non-volatile form of memory that can only be read from. Used for things that remain constant such as computer boot up program etc
Primary storage
Usually RAM
Secondary Storage
Magnetic, solid state or optical non-volatile memory eg hard disk, CD-ROM or flash
Hard disk
A fragile device used to create back ups. Consists of tracks, sectors and platters with concentric tracks created on a magnetic disk that spins from 3600-7200rpm. Has high capacity, fast read write speeds and is relatively cheap per terabyte. Used to store company server data etc
Cloud storage
Expensive but used everywhere. A type of online storage
Solid state drive
Uses electricity programmable non-volatile flash memory and is more durable, portable, consumes less power and has faster read write speeds than a hard disk drive but is also more expensive and has less capacity.
CDs DVDs and BlueRay
Disks created by different laser wavelengths burning small pits that create a spiral track that can be tightly wound to make it longer.
CD-ROM
Read only. Hard printed CD
CD-R
Recordable. A blank CD that can be recorded only once
CD-RW
Rewritable. A CD that can be rewritten again and again
Virtual Memory
A computer uses hard drive space and treats it like its RAM. Not as fast as RAM
