SLR 1.1 Systems architecture Flashcards
What does ALU stand for?
Arithmetic Logic Unit
What is the role of the ALU?
The Arithmetic Logic Unit (ALU) carries out arithmetic operations (maths) or logical comparisons. This allows a program to make decisions.
What does CPU stand for?
Central Processing Unit
What are registers?
“Tiny areas of extremely fast memory located in the CPU normally designed for a specific purpose, where data or instructions are stored temporarily.”
What does PC stand for (in the context of the CPU)?
Program Counter
What is the role of the PC?
“It is a register in the CPU which holds the address of the next instruction to be executed.”
What does ACC stand for?
Accumulator
What is the role of the ACC?
“Holds the results from the ALU (e.g. if a calculation like score = score + 100 or the result of a comparison like if lives == 0)”
What does MAR stand for?
Memory Address Register
What is the role of the MAR?
“It is a register in the CPU that stores the address in memory of the next instruction to be fetched, decoded and executed.”
What does MDR stand for?
Memory Data Register
What is the role of the MDR?
“It is a register in the CPU that stores data being transferred to or from memory.”
What is an FDE cycle?
A Fetch, Decode and Execute cycle
What happens during an FDE cycle?
“The complete process of retrieving an instruction from memory (RAM), decoding it and carrying it out. ”
What does the CPU consist of?
“The CPU is the main part of the computer, consisting of the registers, ALU, cache, and control unit.”
What is “clock speed”?
“The clock speed is the frequency at which the internal clock generates pulses. The higher the clock rate, the faster the computer will carry out the FDE cycle.”
What are cores?
“Cores are the units responsible for the fetch-decode-execute cycle.”
What is the cache?
Cache is extremely fast access memory within the CPU. Frequently used data and instructions are copied to the cache as it is quicker to access than RAM.
What is Von Neumann Architecture?
A traditional computer architecture that forms the basis of most digital computer systems. A single control unit manages program control flow following a linear sequence of ‘fetch-decode-execute’ cycles.
What is an embedded system?
An embedded system is a computer systems with a dedicated function within a larger mechanical or electrical system. For example washing machines, traffic lights, toasters and DVD players all have embedded systems - as do many, many other things!
Name the main parts of a CPU
- Arithmetic Logic Unit (ALU)
- Control Unit (CU)
- Cache
- Registers
Name the main registers a CPU has access to
- Program Counter (PC)
- Memory Address Register (MAR)
- Memory Data Register (MDR)
- Accumulator (ACC)
What does the CU do?
Sends signals to control how data moves around the processor
What are the units for clock speed?
Hertz (cycles per second - this shows how many instructions can be fetched, decoded and executed each second). Modern computers can do billions of FDE cycles per second so are rated in Giga Hertz
