Title: Computer Science / Section 1: Components of a computer / Chapter 3: Types of Processor

Q: Explain what RISC architecture is.
A: Reduced Instruction Set Computers:
Only simple instructions are understood by the CPU, each only one clock cycle long, thus multiplication can be written:
LDA R1, A
LDA R2, B
MULT R1, R2
STO R1 A
- The compiler has to do more work to translate a high level language into RISC machine code
- More RAM is required as there will be more machine code
- More performant
- Less transistors as less instructions understood --> less power consumtion --> good for mobile devices

Q: Explain what CISC architecture is.
A: Complex Instruction Set Computer
CPUs using CISC can understand more instructions, so fewer lines of assembly code can be used, eg to multiply two numbers:
MULT(A,B)
- Some instructions can take multiple cycles
- Less RAM required as less room taken up by Assembly code
- Compiler has less work to do to translate high level code into machine code
- More transistors as larger instruction set --> more power draw --> bad for mobile devices

Q: Explain Von Neuman architecture
A: - Used in convential processors in PCs, servers and embedded systems with only control functions.
- Data and programs share the same memory
- One bus is used to transfer data and instructions
- Programs can be optimised in size

Q: Explain Harvard architecture
A: - Used in digital signal processing (DSP) and in embedded systems, mobile communication systems, audio, speech and image processing systems.
- Instructions and data are held in seperate memories
- Parallel data and instruction buses may be used
- Programs tend to me large

Q: Explain Von Neumann bottlenecking
A: - Data and instructions share same bus
- So next instruction can not be fetched while waiting for data

Q: How do contemporary systems combine Harvard and Von Neumann architectures
A: - Harvard is used betwen level 1 cache and CPU
- Von Neumann is used between CPU and RAM

Q: What is a co-processor?
A: An extra processor used to suplement functions of the CPU, eg calculating floating point integers or graphics processing.

Q: What is a multi-core system
A: A CPU with multiple cores thus it is able to process multiple instrcutions simultaniously and have different tasks running on each core.