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

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