Chapter 1 - Intro and performance

Question 1

Name three (traditional) applications of computing and their characteristics

Answer 1

Personal computers (PC) - delivering good performance for single users

Servers and supercomputers - larger computers build for larger loads and usually only accessible via networks. Small servers usually host websites, supercomputers are used for engineering purposes like weather forecasting, protein structure determination and oil exploration.

Embedded computers - microprocessors that are hidden within bigger devices. An embedded application often has a single purpose and does that single thing really well. Can be found in cars, TVs and even in airplanes.

Question 2

Name two applications of computing in the post-pc era and their characteristics

Answer 2

Personal mobile device (PMD) - Battery operated devices with wireless communication capabilities. Software can be installed in the form of apps and are usually based on touch input.

Cloud Computing and Warehouse Scale Computers (WSC) - Many servers that can fill a warehouse. Companies often rent space to provide SaaS (Software-as-a-Service).

Question 3

Name the eight great ideas in computer architecture

Answer 3

• Design for Moore’s Law
• Use abstraction to simplify design
• Make the common case fast
• Performance via parallelism
• Performance via pipelining
• Performance via prediction
• Hierachry of Memories
• Dependability via redundancy

Question 4

Name two types of system software and their functions

Answer 4

• operating system: an interface between a user program and the hardware. Three important functions are: handling basic I/O operations, allocating and storing memory, providing protected sharing of the computer among multiple applications when running simultaneously
• compilers: translation of high-level programming languages (C,C++, Java, Javascript) to instructions hardware can execute

Question 5

draw the process of converting code from a high level programming language into machine code

Answer 5

high level code (compiler)-> assembly (assembler)-> binary

Question 6

Name the five classic components of a computer

Answer 6

• input
• output
• memory
• datapath
• control

Question 7

Explain what a LCD is and what are it’s basic properties are

Answer 7

a liquid crystal display is a thin low power display that include rod-shaped molecules in a liquid form that can straighten when current is applied so light from a light source can’t pass through. Most LCD use an active matrix meaning there is a tiny transistor switch at each pixel to control the light.

Question 8

List two layers of the memory hierarchy and their properties

Answer 8

• DRAM (dynamic random access memory): Memory location where programs are kept when they are running
• SRAM (static random access memory) / cache memory: a buffer for DRAM. SRAM is faster but can store less data so is more expensive to use.

Question 9

explain the acronym ABI

Answer 9

an Aplication Binary Interface (ABI) is a combination of an instruction set architecture and an operating system interface provided for application programmers

Question 10

Explain what main/primary memory and secondary memory are and what the main difference is between the two

Answer 10

main/primary memory is used to hold data and programs while they run (DRAM) and is volatile, meaning all data is forgotten when the memory loses power.

Secondary memory stores data and programs between runs and is nonvolatile (remembered even when power is removed). Usually secondary memory is stored on magnetic disks or in flash memory.

Question 11

What are the main differences between LAN and WAN?

Answer 11

a Local Area Network (LAN) is a network of computers designed to transfer data within a geographically confined area like a building or even just a floor.

a Wide Area Network (WAN) is a network that is designed to extend over hundreds of kilometers that can span a continent.

Question 12

Explain VLSI

Answer 12

Very large-scale integrated circuit (VLSI) is a term that describes the increase in the number of transistors on an integrated circuits (IC)

Question 13

Describe the manufacturing process of an integrated circuit

Answer 13

With a chemical process the semi-conductor silicon is transformed in three types of materials:

• Excellent conductors of electricity
• Excellent insulators from electricity
• A switch that conducts or insulates electricity based on certain conditions (transistors)

A silicon crystal inglot (a round bar of pure silicon) is sliced into wafers. Various chemicals are placed on the wafers, creating transistors, conductors & insulators. A lot can go wrong on a microscopic level so wafers will always contain a few defect components. Wafers that are done are chopped up or ‘diced’ into chips or ‘dies’. The bad dies are discarded so that the good dies can be packaged and sold. Manufacturers measure success by the yield of a wafer (the percentage of good dies that can be diced out of a wafer)

Question 14

write down the three equations that express the cost of an IC

Answer 14

cost per die = cost per waver / (dies per wafer * yield)

dies per wafer = wafer area / die area

yield = 1 / ((1 + (defects per area * die area / 2))^2)

Question 15

Name two ways performance in terms of speed can be defined

Answer 15

• response time / execution time: the time between the start and completion of a task
• throughput / bandwidth: the amount of work that can be done in a given time

Question 16

with what formula is used to express relative performance

Answer 16

if A is n times as fast as B:

execution time B / execution time A = n
A is faster than B