Lecture 2

Question 1

Multiprogramming abstraction

Answer 1

multi-programming abstraction over many programs means that the execution of
these programs is scheduled such that each runs, bit by bit, but rapid switching
between them gives the impression that all are running smoothly in parallel.

Question 2

Why cant all data reside in the main memory permantely?

Answer 2

First, main
memory is usually too small to store all needed programs and data permanently.
Second, main memory is a volatile storage device that loses its contents when power
is turned off.

Question 3

Where are most programs stored?

Answer 3

most programs (system and application) are stored on a disk until they are loaded into memory.

Question 4

Resource sharing

Answer 4

This resource sharing is made possible by virtual memory and is a memory management function of the OS.

Question 5

extended machine interface

Answer 5

This resource abstraction means that these N programs use virtual memory to share the space
of limited main memory.

Question 6

multiplexing

Answer 6

sharing of main memory by multiple programs

programs are partially loaded

Question 7

OS=kind of virtual machine

Answer 7

each process seems to execute on its own

processor with its own memory, and devices.

Question 8

Java Virtual Machine (JVM)

Answer 8

The Java Virtual Machine (JVM) allows Java code to be portable between various hardware and OS platforms.

Question 9

Concurrency

Answer 9

running of multiple programs on a single CPU

Question 10

Parallelism

Answer 10

the computational speed-up via running multiple programs in parallel on multiple
CPUs.

Question 11

What is the key problem with concurrency?

Answer 11

The key problem with concurrency is that multiple programs (processes) must be
simultaneously executed on a single CPU, and that these multiple processes must
safely interact (e.g. not over-write each other)

Question 12

Multi-threading

Answer 12

a program is split into multiple processes (threads)

that run concurrently on one CPU.

Question 13

multiple virtual processors

Answer 13

a virtual processor is its own virtual machine representing all of the functionality of the underlying
physical processor, meaning that a program can run on a virtual processor just as it would on the physical processor

Question 14

Virtual processors in parallelism

Answer 14

one virtual processor would be run for each physical processor. This N virtual processor for N physical processor setup is used so as the
processes running on each processor are protected from and cannot interfere with each other during the parallel running of the N programs.