Difference Between CISC RISC, Harward & Von-neuman
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This document contains answers to four questions about computer architecture topics: 1. It compares the Von Neumann and Harvard architectures, noting the Von Neumann uses a single memory and Harvard uses separate data/instruction memories. 2. It contrasts RISC and CISC architectures, noting RISC has simpler instructions while CISC has more complex ones. 3. It distinguishes microprocessors from microcontrollers, noting microprocessors are general purpose CPUs while microcontrollers integrate memory and I/O on a single chip. 4. It differentiates between memory-mapped I/O and I/O-mapped I/O, noting memory-mapped I/O uses memory instructions to access I/O while I
Difference Between CISC RISC, Harward & Von-neuman
- 1. LDD: Created By: Kailas Kharse Q1. Diff. Von-Neumann and Hardvard Architecture? Ans: Von -Neumann Hardward Architecture Von -Neumann Hardward Architecture The computer has single storage system(memory) for storing data as well as program to be executed. Separate memories for data and instructions. There is a single pathway used to move both data and instructions between memory, I/O and CPU Two sets of address/data buses between CPU and memory Processor needs two clock cycles to complete an instruction. Pipelining the instructions is not possible with this architecture. Processor can complete an instruction in one cycle if appropriate pipelining strategies are implemented. Less no of control signals More no of control signal. Data Transfer and Instruction Fetch must be scheduled They cannot be performed at same tiem Data Transfer to be performed Simultiniouly on both the buses Q2. Difference Between RISC and CISC? Ans: CISC RISC CISC – Complex Instruction Set Computing. RISC – Reduced Instruction Set Computing. Large no. of instructions, each carry out a different permutation of the same operation. The instructions are at as bare a minimum as possible. Instructions which support some complex operations are made available by the processor’s designer. The user needs to design (through software) some complex operations by them selves. Software burden is less. Software burden is more. Instruction decoding unit size is more. Instruction decoding unit size is less comparatively. Power Consumption is more. Power consumption is less comparatively. Less no. of internal CPU registers. More no. of internal CPU registers. Hence processing is memory intensive. Hence processing is register intensive. Hence impacts CPU operations speed because of frequent memory device’s (slow) access. Has a positive impact on CPU’s processing speed comparitively. Instructions sizes and machine cycles required for executions vary. Mostly instructions sizes and machine cycles required for execution is same.
- 2. CISC RISC Preferable for Complex applications,where power consumption & efficiency can be sidelined. Preferable for applications which need to save power and CPU having efficiency. Many Address Modes are available. Few Addressing modes. Q3. Difference Between Micro-Processor and Micro-Controller? Ans: Micro-Processor Micro-Controller A microprocessor is a general purpose central processing unit of a digital computer. (A chip on a computer) A micro controller is a true computer on a chip. (A computer on a chip) Processors have most of their opcodes moving data from external memory to the CPU. Generally controllers move data and code from internal memory to ALU. The architecture uses data lines more than control lines. The architecture uses control lines more that data lines. No RAM and ROM on the chip RAM and ROM along with processor are present It has single or dual bit instructions It has multi bit instructions Access time to memory and I/O devices is high Access time to memory and I/O devices is less Less number of pins are multiplexed More number of pins are multiplexed Consists of single memory map for data and code Consists of separate memory map for data and code High clock frequency Low clock frequency External peripheral are to interfaced to enhance functionality These are application specific and so no need of external peripherals
- 3. Micro-Processor Micro-Controller Can perform all the computation in any field Can perform only a specific task Cost is high Cost is low I/O communication needs external peripherals I/O communication ports are inbuilt Serial communication is not possible Serial communication ports are inbuilt Boolean operations cannot be performed directly Boolean operations can be performed directly Q4. Difference between I/O Mapped I/O and Memory Mapped I/O? Ans: Memory Mapped I/O I/O Mapped I/O Memory Mapped I/O is mapped into the same address space as program memory and/or user memory, and is accessed in the same way. I/O Mapped I/O uses a separate, dedicated address space and is accessed via a dedicated set of microprocessor instructions. Same address bus to address memory and I/O devices Different address spaces for memory and I/O devices Access to the I/O devices using regular instructions Uses a special class of CPU instructions to access I/O devices Most widely used I/O method MEMR`, MEMW`. IOR`,IOW`,MEMR`,MEMW` Specific Purpose Application Genereral Purpose Application No IN and OUT instructions Saperate IO peripherial instructions IN and OUT More Decoding is required Less decoding is required Processor provides more address lines for accessing memory Processor provides saperate address range for memory and I/O. $cat /proc/iomemory $cat /proc/ioports