Hardware And Software Flashcards
The CPU controls
The operation of the CPU and other hardware
The storage and transfer of data
The FDE cycle
RAM is
Random Access Memory that is volatile and stores the programs and data currently being used
ROM is
Read Only Memory that is non volatile and stores the booting up part of the OS program
Cache is
High speed fast access RAM that is placed close to the CPU it stores the most recently and frequently accessed files it is also volatile
Name the registers
The current instruction register The memory data register The memory address register The program counter The accumulator
The instruction register
Holds the instruction currently being executed
The memory data register
Holds the piece of data that has been fetched from memory
The memory address register
Holds the address of the next piece of memory to be fetched
The program counter
Holds the location of the next instruction to be fetched it is automatically incremented between supplying the address of the next instruction being executed and the instruction being executed
The address bus
Takes the memory address to the ram
The data bus
Takes the data from the memory to the CPU
The five steps of the Fetch stage are
- The program counter copies the address of the next instruction it contains to the MAR
- The MAR places the address to be used on the address bus
- The MAR triggers a read signal that causes main memory to place the instruction being asked for on the data bus
- The instruction on the data bus is loads into the MDT
- The MDR copies the instruction to the CIR
In what step of the FDE does the CPU decode the instruction and prepares various areas within the chip in readiness of the next step
Decode
What happens in the execute step
Processing takes place the instruction is executed and the result is stored in another register and the CPU starts another cycle
What are the four key factors about CPU architecture
Cores
Clock speed
Cache size
Processor type
What is a Core
A core is a processing unit which contains an ALU, control unit and registers. They communicate with each other using channels which use up some of the extra speed they provide
What is Clock Speed
Clock speed indicates how fast the CPU can run. It is measured in mega or giga hertz and corresponds with how many instruction cycles the CPU can deal with a second. It can be increased through over clocking but there are limits as the CPU cannot always keep up with the overclocked speed and overheat
How can cache improve the CPUs performance
Increasing the cache which is fast access RAM placed close to the CPU means more instructions that the CPU uses regularly can be stored there making them quicker to access improving the CPU
Advantages of tape streamers
Cheap per Mb of storage
Can store large amounts of data(over 100GB)
Can be set up to do the back up overnight or over the weekend
Robotic archive and backup systems can swap tapes in and out automatically
Disadvantages to tape streamers
Serial access means data can be quite slow to access
Need a special piece of equipment to record and read data
Less robust than other media as the tape can easily break
