Chapter 1
Classes of computing Applications and their
characteristics
Computers used in 3 different classes
- Personal computers (PC):
Designed for use by an individual. Incorporating a graphics display, keyboard and
mouse.
- Servers:
A computer used for running larger programs for multiple users, often
simultaneously. Typically accessed only via a network. Oriented to carrying large
workloads, which may consist of either single complex applications, or handling
many small jobs. Applications usually based on software from another source, but
often modified or customized for a function.
Supercomputers consist of tens of thousands of processors and many terabytes of
memory (1012 bytes)
- Embedded computers:
Computer inside another device used for running one predetermined application or
collection of software.
PostPC-era
- Personal mobile devices (PMD):
Replacing pcs. Small wireless devices to connect to the internet. Rely on batteries for
power, software installed via apps.
- Cloud computing:
Replacing servers. Large collection of servers that provide services over the internet.
Software: portion of application running on PMD, portion in the cloud.
Eight great ideas in computer architecture
Design for Moore’s law
States that every 18-24 months the integrated circuit resources double.
Use abstraction to simplify design
Major productivity technique: use abstractions to represent the design at different levels.
Make the common case fast
Tend to enhance performances better than optimizing the rare case.
Performance via parallelism
Get more performance by performing operations in parallel.
,Performance via pipelining
Particular pattern of parallelism.
Performance via prediction
In some cases, it is faster to guess and start working instead of waiting until you know for sure.
Hierarchy of memories
Fastest, smallest and most expensive at the top. Slowest, largest and cheapest at the bottom.
Gives the illusion that the main memory is nearly as fast as the top and nearly as big and cheap as
the bottom.
Dependability via redundancy
Make systems dependable by including redundant components that can take over when a failure
occurs and to help detect failures.
Below your program 3
Layers of software organized: 1 2
1. Hardware
2. Systems software: provides services that are commonly useful
3. Application software
2 types of system software central to every computer:
- Operating system: interfaces between a user’s program and hardware. Supervising program
that manages the resources of a computer for the benefit of the programs that run on the
computer.
Handling basic input and output operations
Allocating storage and memory
- Compiler: program that translates high level language statements into assembly language
statements.
From a high-level language to the language of hardware
Computer uses binary language: numbers in base 2 (1 and 0).
Binary digit: bit, one of the 2 numbers 0 or 1.
Instructions: command that computer hardware understands and obeys.
Programs to translate symbolic to binary: assembler
Symbolic language: assembly language
Binary language: machine language
Assembly language requires the programmer to write one line for every instruction the
programmer needs to think like a computer.
High-level programming language: composed of words and algebraic notation that can be
translated by a compiler to assembly language.
High-level Assembly Binary
Compiler Compiler
A+B add A, B 1000110010100000
, High-level languages think in more natural language
- Allow languages to be designed according to their intended use.
- Improved programmer productivity
- Allow programs to be independent of the computer on which they were developed.
Under the covers
2 key components:
- Input devices: mechanism through which the computer is fed information
- Output devices: mechanism that conveys the result of a computation to a user
5 classic components:
- Input
- Output
- Memory
- Datapath
- Control Processor
Display:
Often liquid crystal display (LCD): thin, low-power, controls the transmission of light.
Most LCDs use an active matrix that has a tiny transistor switch at each pixel control transmission
of light at each pixel.
Pixel: smallest individual picture element, can be represented as a matrix of bits: bit map.
Computer hardware support for graphics: raster refresh buffer/frame buffer to store bit map.
Many touchscreens use capacitive sensing: people are electrical conductors touching distracts the
electrostatic field of the screen change of capacitance.
Integrated circuit: chip, device combining dozens to millions of transistors.
Central processor unit: CPU, processor, active part of the computer, contains Datapath and control.
Datapath: component of processor that performs arithmetic operations.
Control: component of processor that commands the Datapath, memory, I/O-devices according to
instructions of the program.
Memory: storage area in which programs are kept when they are running and contains data needed
by running programs, built from DRAM chips.
DRAM: dynamic random-access memory. Memory built as integrated circuit. Provides random
access to any location.
Cache memory: consists of small, fast memory. Acts as a buffer for DRAM.
SRAM: static random-access memory. Memory built as integrated circuit. Faster, less dense than
DRAM.
Classes of computing Applications and their
characteristics
Computers used in 3 different classes
- Personal computers (PC):
Designed for use by an individual. Incorporating a graphics display, keyboard and
mouse.
- Servers:
A computer used for running larger programs for multiple users, often
simultaneously. Typically accessed only via a network. Oriented to carrying large
workloads, which may consist of either single complex applications, or handling
many small jobs. Applications usually based on software from another source, but
often modified or customized for a function.
Supercomputers consist of tens of thousands of processors and many terabytes of
memory (1012 bytes)
- Embedded computers:
Computer inside another device used for running one predetermined application or
collection of software.
PostPC-era
- Personal mobile devices (PMD):
Replacing pcs. Small wireless devices to connect to the internet. Rely on batteries for
power, software installed via apps.
- Cloud computing:
Replacing servers. Large collection of servers that provide services over the internet.
Software: portion of application running on PMD, portion in the cloud.
Eight great ideas in computer architecture
Design for Moore’s law
States that every 18-24 months the integrated circuit resources double.
Use abstraction to simplify design
Major productivity technique: use abstractions to represent the design at different levels.
Make the common case fast
Tend to enhance performances better than optimizing the rare case.
Performance via parallelism
Get more performance by performing operations in parallel.
,Performance via pipelining
Particular pattern of parallelism.
Performance via prediction
In some cases, it is faster to guess and start working instead of waiting until you know for sure.
Hierarchy of memories
Fastest, smallest and most expensive at the top. Slowest, largest and cheapest at the bottom.
Gives the illusion that the main memory is nearly as fast as the top and nearly as big and cheap as
the bottom.
Dependability via redundancy
Make systems dependable by including redundant components that can take over when a failure
occurs and to help detect failures.
Below your program 3
Layers of software organized: 1 2
1. Hardware
2. Systems software: provides services that are commonly useful
3. Application software
2 types of system software central to every computer:
- Operating system: interfaces between a user’s program and hardware. Supervising program
that manages the resources of a computer for the benefit of the programs that run on the
computer.
Handling basic input and output operations
Allocating storage and memory
- Compiler: program that translates high level language statements into assembly language
statements.
From a high-level language to the language of hardware
Computer uses binary language: numbers in base 2 (1 and 0).
Binary digit: bit, one of the 2 numbers 0 or 1.
Instructions: command that computer hardware understands and obeys.
Programs to translate symbolic to binary: assembler
Symbolic language: assembly language
Binary language: machine language
Assembly language requires the programmer to write one line for every instruction the
programmer needs to think like a computer.
High-level programming language: composed of words and algebraic notation that can be
translated by a compiler to assembly language.
High-level Assembly Binary
Compiler Compiler
A+B add A, B 1000110010100000
, High-level languages think in more natural language
- Allow languages to be designed according to their intended use.
- Improved programmer productivity
- Allow programs to be independent of the computer on which they were developed.
Under the covers
2 key components:
- Input devices: mechanism through which the computer is fed information
- Output devices: mechanism that conveys the result of a computation to a user
5 classic components:
- Input
- Output
- Memory
- Datapath
- Control Processor
Display:
Often liquid crystal display (LCD): thin, low-power, controls the transmission of light.
Most LCDs use an active matrix that has a tiny transistor switch at each pixel control transmission
of light at each pixel.
Pixel: smallest individual picture element, can be represented as a matrix of bits: bit map.
Computer hardware support for graphics: raster refresh buffer/frame buffer to store bit map.
Many touchscreens use capacitive sensing: people are electrical conductors touching distracts the
electrostatic field of the screen change of capacitance.
Integrated circuit: chip, device combining dozens to millions of transistors.
Central processor unit: CPU, processor, active part of the computer, contains Datapath and control.
Datapath: component of processor that performs arithmetic operations.
Control: component of processor that commands the Datapath, memory, I/O-devices according to
instructions of the program.
Memory: storage area in which programs are kept when they are running and contains data needed
by running programs, built from DRAM chips.
DRAM: dynamic random-access memory. Memory built as integrated circuit. Provides random
access to any location.
Cache memory: consists of small, fast memory. Acts as a buffer for DRAM.
SRAM: static random-access memory. Memory built as integrated circuit. Faster, less dense than
DRAM.
