Section 1 - Chapter 3: Types of Processors Flashcards
What is a von Neumann architecture?
It specifies the basic components of the computer and processor in which a shared memory and bus is used for both data and instruction.
What is the stored program concept?
It can be defined as: machine code instructions are fetched and executed serially by a processor that performs arithmetic and logical operations.
- A program must be resident in main memory to be executed.
- The machine code instructions are fetched from memory one at a time, decoded and executed in the processor.
What is the von Neumann machine?
The same data bus is used to transfer both data and instructions. Similarly, a single address bus is used to transfer the addresses of data and instructions. The same word length is used for all memory, whether it holds data and instructions.
What is the Harvard Architecture?
It is a computer architecture with physically separate memories for instructions and data. Harvard Architecture is used extensively with embedded Digital Signal Processing (DSP) systems.
Name me some DSP applications
Includes audio and speech signal processing, sonar and radar signal processing, biomedical processing, seismic data processing and digital image processing.
What are examples of two different memories than can have different characteristics?
- In embedded systems, instructions may be held in read-only memory while data memory requires read-write memory.
- In some systems, there is much more instruction memory than data memory, so a larger word size is used for instructions
- the instruction address bus may be wider than the data bus
What are embedded systems?
Embedded systems include special - purpose computers built into devices often operating in real time, such as those used in navigation systems.
Why is Harvard Architecture faster than von Neumann architecture?
Because data and instructions can be fetched in parallel instead of competing for the same bus.
Comparison if von Neumann and Harvard architecture.
Von Neumann:
- Used in conventional 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.
Harvard:
- Used in digital signal processing and in embedded systems.
- Instructions and data are held in separate memories
- Parallel data and instruction buses may be used
- Programs tend to be large
What are contemporary processor architectures?
Modern high-performance CPU chips incorporate aspects of both von Neumann and Harvard architecture. In one design, there is one main memory for holding both data and instructions, but CPU cache memory is divided into an instruction cache and a data cache. Harvard architecture is used as the CPU accesses the cache.
What is Complex Instruction Set Computers (CISC)?
A large instruction set is used to accomplish tasks in as few lines of assembly language as possible.
Advantage of CISC
The compiler has very little work to do to translate a high-level statement into machine code. Because the code is relatively short, very little RAM is required to store the instructions.
Disadvantage of CISC
Many specialised equipment had to be built into the hardware .
What is Reduced Instruction Set Computers (RISC)?
Only simple instructions, each taking one clock cycle, can be executed. RISC has largely replaced CISC as a processor design, but CISC is still used for microcontrollers and embedded systems.
Advantage of RISC
Because each instruction takes the same amount of time, pipelining is possible.
