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Hardware and virtual machine

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Logic gates and circult design

Logic gates:

A component of a logical circuit that can perform a Boolean operation (logical function).

 NOT Gate: Aˉ=X\text { NOT Gate: } \bar{A}=X
 NAND Gate: A⋅B‾=X\text { NAND Gate: } \overline{A \cdot B}=X
 NOR Gate: A+B‾=X\text { NOR Gate: } \overline{A+B}=X
 XOR Gate: A⋅Bˉ+Aˉ⋅B=X\text { XOR Gate: } A \cdot \bar{B}+\bar{A} \cdot B=X

Half-Adder

A logic circult whose output is dependent only on the input values.

Boolean algebra

Aˉ‾=A\overline{\bar{A}}=A
1.A=A0+A=A\begin{aligned}& 1 . A=A \\& 0+A=A\end{aligned}
0.A=01+A=1\begin{aligned}& 0 . A=0 \\& 1+A=1\end{aligned}
A⋅Aˉ=0A+Aˉ=1\begin{aligned}& A \cdot \bar{A}=0 \\& A+\bar{A}=1\end{aligned}
(A⋅B)⋅C=A⋅(B⋅C)(A+B)+C=A+(B+C)\begin{aligned}& (A \cdot B) \cdot C=A \cdot(B \cdot C) \\& (A+B)+C=A+(B+C)\end{aligned}
A+B⋅C=(A+B)⋅(A+C)A⋅(B+C)=A⋅B+A⋅C\begin{aligned} & A+B \cdot C=(A+B) \cdot(A+C) \\ & A \cdot(B+C)=A \cdot B+A \cdot C \end{aligned}
A⋅(A+B)=AA+A⋅B=A\begin{aligned}& A \cdot(A+B)=A \\& A+A \cdot B=A\end{aligned}
(A⋅B‾)=Aˉ+Bˉ(A+B‾)=Aˉ⋅Bˉ\begin{aligned}& (\overline{A \cdot B})=\bar{A}+\bar{B} \\& (\overline{A+B})=\bar{A} \cdot \bar{B}\end{aligned}

CISC and RISC

What is Instruction Set?

Points to note

See more at https://learnlearn.uk/alevelcs/risc-vs-cisc-processors/

Pipelining

Pipelined processor and interrupt handling

The basic computer architectures

SISD

Single Instruction Stream Single Data Stream
• The functioning is purely sequential with no parallelism
• Only one single process unit
• A single instruction is executed on a single data stream
- The original Von Neumann Architecture was SISD.
• Advantages:
• Cheap
• Low power consumption
• Disadvantages:
• Limited speed due to being a single core
• User:
• Microcontrollers
• Older mainframes

SIMD

Single Instruction Multiple Data (SIMD)
• A single instruction is executed on multiple different pieces of data
• These instructions can be performed sequentially, taking advantage of pipelining, or in parallel using multiple processors.
• Modern GPUs, containing Vector processors and array processors, are commonly SIMD systems.

SIMD

Single Instruction Multiple Data

Advantages:
Very efficient where you need to perform the same instruction on large amount of data

Disadvantages:
Limited to specific applications

Uses:
GPUs
Scientific processing

MISD

Multiple instruction single data
• Multiple processors work on the same data set performing different instructions at the same time
• Advantages:
• Useful where real time fault detection is critical
• Disadvantages
• Very limited application so not available commercially
Uses
• Space shuttle flight control systems

MIMD

Multiple instruction multiple data
• Multiple processors perform operations on different pieces of data
• This means that serval different instructions can be executed at the same time, using different data streams
• Advantages:
• Great for situations where multitasking is required
• Disadvantages:
• Much more complicated architecture so more expensive
• Uses
Most modern PCs, laptops, smart phones

Massively parallel computer systems

• Used by large organizations for computations involving highly complex mathematical processing.
• Supercomputer
• Multiple processors
• Cluster
• Multiple computers
• Key features: extremely large number of individual processors working in parallel.

Flip-Flop circults

Virtual machines

System virtual machine

System virtual machines

Process virtual machine

Java virtual machine

Benifits of VM

from mark scheme

drawbacks

from mark scheme