Computer systems Flashcards
What is the are hardware and software ?
Hardware is the physical components that make up the computer. Software is the programs or applications that a computer runs.
What are embedded systems
Embedded systems are computers built into other devices. They are dedicated to one task , embedded systems are usually easier to design , cheaper to produce and more efficient at doing their task than a general computer.
What is the CPU?
It processes all the data and instructions that make the system work. The speed at which it works depends on clock speed , number of cores and cache size.
What is the function of the Control Unit (CU)?
The CU is in overall control of the CPU . It executes programs by following the fetch-decode-execute cycle . It also controls the flow of data inside and outside of the CPU.
What is the function of the ALU ?
It performs all the basic maths calculations It also performs all the logic operations such as AND , OR and NOT and binary shifts.
What is the function of Cache
The cache is very fast memory. It stores regularly stored data so the CPU can access it quickly . The CPU checks the cache first when it requests data and if not , it goes to the RAM.
Why isn’t the whole of the memory cache memory?
It has a very low capacity and is very expensive compared to RAM . There are different levels : L1 has the smallest capacity but is the quickest going down to L3.
What is the program counter ?
The PC holds the memory address of the next instruction that is to e executed.
What is the accumulator ?
It stores the immediate results of calculations in the ALU
What is the memory address register ?
The MAR holds any memory address about to be used by the CPU . The address might point to data or a CPU instruction.
What is the function of the memory data register?
The MDR holds the actual data or instruction .
What is the function of memory ?
The memory holds the program instructions and the program data
What is Von Neumann ‘s architecture ?
It describes a system where the CPU runs programs stored in memory. Programs consists of instructions and data which are stored in memory addresses.
What happens in fetch ?
Copy address from the program counter to the MAR . Copy the instruction stored in MAR address to the MDR. Increase the program counter to point to the address of the next instruction.
What happens in decode ?
The instruction in the MDR is then decoded by the CU . The CU can then prepare for the next step.
