Free Essay

Computer Memory

In:

Submitted By qzeshan
Words 282
Pages 2
The Deadlock Problem
Law passed by the Kansas Legislature in early 20th century:
“When two trains approach each other at a crossing, both shall come to a full stop and neither shall start upon again until the other has gone.”
Neil Groundwater has the following to say about working with Unix at Bell Labs in 1972:
... the terminals on the development machine were in a common room ... when one wanted to use the line printer. There was no spooling or lockout. pr myfile > /dev/lp was how you sent your listing to the printer. If two users sent output to the printer at the same time, their outputs were interspersed. Whoever shouted.
“line printer!” first owned the queue.
1
Deadlock or Deadly Embrace
 Permanent blocking of a set of processes that either compete for system resources or communicate with each other
– Several processes may compete for a finite set of resources
– Processes request resources and if a resource is not available, enter a wait state
– Requested resources may be held by other waiting processes
– Require divine intervention to get out of this problem
 A significant problem in real systems, because there is no efficient solution in the general case
 Deadlock problem is more important because of increasing use of multiprocessing systems (like real-time, life support, vehicle monitoring, multicore utilization, grid processing)
 Important in answering the question about the completion of a process
 Deadlocks can occur with
– Serially reusable (SR) resources – printer, tape drive, memory
 A finite set of identical units, with the number of units constant
 Can be used safely by only one process at a time and are not depleted by that use
 Units acquired by processes, used, and re

Similar Documents

Premium Essay

Computer Memory

...Computer Memory 1.Introduction: Just like humans, computers rely a lot on memory. They need to process and store data, just like we do. However, computers store data in digital format, which means the information can always be called up exactly the way it was stored. computer memory - an electronic memory device; "a memory and the CPU form the central part of a computer to which peripherals are attached" 1.1History of memory: In the early 1940s, memory technology mostly permitted a capacity of a few bytes. The first electronic programmable digital computer, the ENIAC, using thousands of octal-base radio vacuum tubes, could perform simple calculations involving 20 numbers of ten decimal digits which were held in the vacuum tube accumulators. The next significant advance in computer memory came with acoustic delay line memory, developed by J. Presper Eckert in the early 1940s. Through the construction of a glass tube filled with mercury and plugged at each end with a quartz crystal, delay lines could store bits of information within the quartz and transfer it through sound waves propagating through mercury. Delay line memory would be limited to a capacity of up to a few hundred thousand bits to remain efficient. Two alternatives to the delay line, the Williams tube and Selectron tube, originated in 1946, both using electron beams in glass tubes as means of storage. Using cathode ray tubes, Fred Williams would invent the Williams tube, which would be the first random...

Words: 3247 - Pages: 13

Premium Essay

Computer Memory

...sectors. The OS creates a directory which will record the specific location of files. When you save a file, the OS moves the read/write head of the drive towards empty sectors, records the data and writes an entry for the directory. Later on, when you open that file, the OS looks for its entry in the directory, moves the read/write heads to the correct sector, and reads the file in the RAM area. However, formatting erases any existing files on a disk, so do not format disks on which data that you don't want to lose is stored. The OS allows you to create one or more partitions on your hard drive, in effect dividing it into several logical parts. Partitions let you install more than one operating system (e.g. Windows and Linux) on your computer. You may also decide to split your hard drive because you want to store the OS and programs on one partition and your data files on another; this allows you to reinstall the OS when a problem occurs, without affecting the data partition. The average time required for the read/write heads to move and find data is called seek time (or access time) and it is measured in milliseconds (ms); most...

Words: 1272 - Pages: 6

Free Essay

Computer Memory Hacking

...Computer Memory Hacking By: Christopher Slaton Professor Jamaz Hall CIS 106 The corruption of memory occurs in a program when the contents of a memory location are unintentionally modified due to programming errors; this is termed violating memory safety. Later in the program when the corrupted contents are used it usually leads to program crash or to erratic computer behavior. About 10% of application crashes on Windows systems are due to heap corruption. There are a host of applications that are designed to efficiently develop system software. Programming languages such as C and C++ contain powerful features memory management and pointer arithmetic. These features are designed for developing efficient applications and system software. Memory corruption is one of the most intractable class of programming errors. Computer memory hacking is the practice of modifying computer hardware and software to accomplish a goal outside of the creators original purpose. People who engage in computer hacking activities are often called hackers. While some hackers aren’t worried about the or concerned about the consequences of there actions, there is little debate about the fact that hacking has several negative effects. Businesses and governments spend an enormous amount of money to prevent damage from hacking. Hacking on a large scale can cause extensive website damage, an long lasting inconvenience. Computer hacking is largely common among teenagers and young adults. Many...

Words: 642 - Pages: 3

Premium Essay

Computer Memory

...Computer Memory Hacking Student’s name: Institutional affiliation: Computer Memory Hacking RAM hacking can be described as a form of hacking that makes it hard for a computer system to process encrypted data. In such a scenario of hacking, all the data that is stored in the attacked computer's RAM is left completely vulnerable for manipulation by unauthorized access in its processing stages. In order to prevent RAM hacking, all the data that needs to be processes and already in the computer's RAM must be entirely encrypted (Philipp et al., 2010, p. 35). There are several tools that hackers can use when RAM hacking, which include several programs and utilities. The most common tools of RAM hacking is Nmap and Metasploit. Nmap, also referred to as the swiss army knife of RAM hacking or any other hacking, is one of the best effective port scanner tool numerous functions. In its hacking, Nmap is used in a footprinting phase to scan the ports of the remote computer, where it finds out which ports are open in order to compromise their access. Metasploit, on the other hand, is also an effective tool in RAM hacking as it commands a large database of exploits. In addition, it offers thousands of exploits codes that are useful on attacking web servers and computers (Levy, 2010, p.28). This is a hacking tool that hacks not only the RAM, but the almost entire part of a computer. Hackers always attack and succeed where they...

Words: 628 - Pages: 3

Free Essay

A Look Into Computer Memory

...A Look into Computer Memory   Table of Contents Abstract 3 A Look into Computer Memory 4 Memory Hierarchy 4 Allocation Policies 5 Relocation Policies 6 Hit and Hit Ratio 6 Modern Computer Applications 7 Conclusion 7 References 8   Abstract The memory of a computer is a key component of the overall architecture of a computer. Several types of memory exist with the architecture of the computer which collectively is known as the memory hierarchy. The use of the memory hierarchy, placing and moving information, is effected by the allocation and relocation policies. How well these policies allow the processor to find the information it is looking for, known as a hit, is determined by the hit ratio. The modern processor available today relies on memory hierarchy to maintain their high performance. The paper will take a look at how these various pieces and policies work together within the architecture of a computer. A Look into Computer Memory Memory plays a key role in the modern processor. The memory hierarchy is the foundation for which the allocation and relocation policies function upon. These policies work to provide the needed information in the proper memory location to attempt to maintain a high hit ratio to avoid processor delay. Regardless of the speed of a modern processor, a low hit ratio adds delay to the high performance processor. Memory Hierarchy Memory in a computer varies in size, speed with regards to access time and, just as importantly,...

Words: 1554 - Pages: 7

Premium Essay

Computer Memory Hacking

...it comes to the term “hacking” whether it is someone’s memory or RAM, everyone starts to worry about their information. What is “hacking of memory”? It is to circumvent security and break into with malicious intent. It is finding a way into your computer without your permission let alone your knowledge to gain information like banking and documents. On a larger scale it also means getting into banks and big companies like Target or more recently Sony to gain access to accounts and thus steal money/information. There is however steps to prevent this from happening with the right equipment. To know how to prevent someone from hacking into your computer you first have to know what tools they use. There are a plethora of programs that are used some being dSniff, Netcat and John the Ripper. DSniff passively monitors a network for interesting data like passwords, e-mails, files etc. Netcat is designed to be a dependable back-end that has features that include port scanning, transferring files, port listening, and worse used as a backdoor. John the Ripper is a popular password testing and breaking programs but hackers would use it for the later. For dSniff, someone would have to first have access to your computer by the user either downloading the program by accident or the hacker pushing it to you. Then the tool is activated and monitors your computer for the right information. John the Ripper is used to break into computers and external hard drives. It would not be a tool that would...

Words: 774 - Pages: 4

Premium Essay

Computer Memory Hacking

...Computer Memory Hacking NAME Professor CIS 106 November 20, 2014 Technology continues to evolve exponentially. However these technological advancements continue to pose a threat to both individuals and information resources of companies and governments. There is therefore the need to protect one’s data and information due to the emerging threats and risks. Hacking is where third parties create a backdoor version of a hardware and software so as to manipulate or unlock hidden functionalities on a machine. Most of these hacks are open source and free soft wares. These hacks manipulate the firmware update option on many devices to run and install themselves. Many researchers have found out that breaking into a computer’s encrypted hard drive is very easy with the help of the right tools. A research by Princeton University revealed how low tech hackers access even the most well protected computers (Jordan Robertson 2008). This paper details how encryption was coveted for a long time as a vital shield against hackers, but can be manipulated by altering the operations of the memory chips. This paper outlines just how vulnerable the data we store on our computers and laptops is to possible hacking. Through freezing the Dynamic Random Access Memory (DRAM) chip, which is the most frequently used memory chip in personal gadgets. Freezing DRAM makes it retain data for many hours way after the machine loses its power. This data includes the keys used...

Words: 901 - Pages: 4

Premium Essay

Characteristics Of Computer Memory

...which is computer memory. In binary form is the content of memory. In order to carry out all kinds of operations, memory offers input to the processors. Thus, the processors save the results into memory (World of Computing, 2013). The characteristic of computer memory which are electrical characteristics, the manufacturing technology of the device depend on the voltage and current requirements. It is not main concern of the voltage due to most of the semiconductor memory device manipulate at TTL voltage levels. In addition, speed also is the characteristic of computer memory. There is a limit time to delay between the usability of stabilize and accurate of the data on the data lines because of the...

Words: 763 - Pages: 4

Free Essay

Computer Memory Hacking

...Hill CIS 106 Professor J. Merritt Assignment 1: Computer Memory Hacking November 15, 2015 As the years go by technology will continually advance at a superb rate. With that comes many risks. The invasion of privacy for individuals and business owners is a concerning matter. The target hackers are aiming for these days is the computer memory. Third party individuals create a backdoor to the hardware and software of a machine to gain access to the hidden functions they may hold. Hackers break into computer systems by exploiting security vulnerabilities, such as poor configuration of web servers, disabled security controls, or poorly chosen or default passwords. Hackers may modify existing computer resources and settings without consent and, in so doing, cause damage or disruption to computer systems or networks. It is easily attainable since its open source and free software. The ethical issues surrounding hacking, stem from several sources mainly dealing with order and control, and information ownership. What is difficult to decipher from all the media hoopla surrounding the terms, "hacker" and "hacking" is both the simultaneous sensationalism and the condemnation of said activities. Of course just recently, even a movie was made and was appropriately called Hackers. The term and all that it implies has truly entered our popular consciousness when Hollywood has made a box office movie on it. As the advancement of computer technologies and systems of information become increasingly...

Words: 997 - Pages: 4

Premium Essay

Assignment 1: Computer Memory Hacking

...1: Computer Memory Hacking Professor Carl Brown CIS 106 Technology continues to evolve exponentially. However these technological advancements continue to pose a threat to both individuals and information resources of companies and governments. There is therefore the need to protect one’s data and information due to the emerging threats and risks. Hacking is where third parties create a backdoor version of a hardware and software so as to manipulate or unlock hidden functionalities on a machine. Most of these hacks are open source and free soft wares. These hacks manipulate the firmware update option on many devices to run and install themselves. Many researchers have found out that breaking into a computer’s encrypted hard drive is very easy with the help of the right tools. A research by Princeton University revealed how low tech hackers access even the most well protected computers (Jordan Robertson 2008). This paper details how encryption was coveted for a long time as a vital shield against hackers, but can be manipulated by altering the operations of the memory chips. This paper outlines just how vulnerable the data we store on our computers and laptops is to possible hacking. Through freezing the Dynamic Random Access Memory (DRAM) chip, which is the most frequently used memory chip in personal gadgets. Freezing DRAM makes it retain data for many hours way after the machine loses its power. This data includes the keys used to unlock encryptions. If the memory chip...

Words: 901 - Pages: 4

Premium Essay

Computer Crime Journal

...Journal - Week 1, Due 09.28.2014 Beginner’s Guide to Internet Protocol (IP) Addresses Beginner’s Guide to Internet Protocol (IP) Addresses. (2011, Mar. 04). Retrieved on September 26. 2014 from ICANN site: https://www.icann.org/resources/files/ip-addresses-beginners-guide-2011-03-04-en The Beginner’s Guide to IP Addresses is a publication by the Internet Corporation for Assigned Names and Numbers (ICANN), the private sector, non-profit corporation which assumes responsibility for IP address space allocation, protocol parameter assignment, domain name system management, and root server system management functions. The publication is part of the Beginner’s Guide series, published in the interest of educating new users about internet issues. The document details IP addresses, why we need them, protocol version history, implementation/distribution methods, and how these topics affect users. This particular concept is not new to me, but reading the document provided a ‘refresher course’ on topics that I have not recently studied. I use this information and technology on a daily basis - but through the course of use it is easy to step away from the fundamental details. In follow up reading, I find myself curious about the success of implementing IPv6 addressing. I know that it can be done, but have not seen a great deal of evidence that it is being done. As of June, 2014 the percentage of users accessing Google via IPv6 reached a milestone. 4%. While the 4% mark...

Words: 7665 - Pages: 31

Free Essay

Nios-Multicore Accelerator

...Creating Multiprocessor Nios II Systems Tutorial Creating Multiprocessor Nios II Systems Tutorial 101 Innovation Drive San Jose, CA 95134 www.altera.com TU-N2033005-2.0 Document last updated for Altera Complete Design Suite version: Document publication date: 11.0 June 2011 Subscribe © 2011 Altera Corporation. All rights reserved. ALTERA, ARRIA, CYCLONE, HARDCOPY, MAX, MEGACORE, NIOS, QUARTUS and STRATIX are Reg. U.S. Pat. & Tm. Off. and/or trademarks of Altera Corporation in the U.S. and other countries. All other trademarks and service marks are the property of their respective holders as described at www.altera.com/common/legal.html. Altera warrants performance of its semiconductor products to current specifications in accordance with Altera’s standard warranty, but reserves the right to make changes to any products and services at any time without notice. Altera assumes no responsibility or liability arising out of the application or use of any information, product, or service described herein except as expressly agreed to in writing by Altera. Altera customers are advised to obtain the latest version of device specifications before relying on any published information and before placing orders for products or services. Creating Multiprocessor Nios II Systems Tutorial June 2011 Altera Corporation Contents Chapter 1. Creating Multiprocessor Nios II Systems Introduction to Nios II Multiprocessor Systems . . . . . . . . . . . . . . . . . . . . . . ...

Words: 12538 - Pages: 51

Premium Essay

Abcdef

...Morning Exam Part2: Trial Exam Set INFORMATION-TECHNOLOGY PROMOTION AGENCY, JAPAN FE Exam Preparation Book Vol. 1 Table of Contents Part 1 Chapter 1 PREPARATION FOR MORNING EXAM Computer Science Fundamentals 1.1 Basic Theory of Information 1.1.1 Radix Conversion 1.1.2 Numerical Representations 1.1.3 Non-Numerical Representations 1.1.4 Operations and Accuracy Quiz 1.2 Information and Logic 1.2.1 Logical Operations 1.2.2 BNF 1.2.3 Reverse Polish Notation Quiz 1.3 Data Structures 1.3.1 Arrays 1.3.2 Lists 1.3.3 Stacks 1.3.4 Queues (Waiting lists) 1.3.5 Trees 1.3.6 Hash Quiz 1.4 Algorithms 1.4.1 Search Algorithms 1.4.2 Sorting Algorithms 1.4.3 String Search Algorithms 1.4.4 Graph Algorithms Quiz Questions and Answers 2 3 3 7 10 11 14 15 15 18 21 24 25 25 27 29 30 32 34 37 38 38 41 45 48 50 51 i Chapter 2 Computer Systems 2.1 Hardware 2.1.1 Information Elements (Memory) 2.1.2 Processor Architecture 2.1.3 Memory Architecture 2.1.4 Magnetic Tape Units 2.1.5 Hard Disks 2.1.6 Terms Related to Performance/ RAID 2.1.7 Auxiliary Storage / Input and Output Units 2.1.8 Input and Output Interfaces Quiz 2.2 Operating Systems 2.2.1 Configuration and Objectives of OS 2.2.2 Job Management 2.2.3 Task Management 2.2.4 Data Management and File Organization 2.2.5 Memory Management Quiz 2.3 System Configuration Technology 2.3.1 Client Server Systems 2.3.2 System Configurations 2.3.3 Centralized Processing and Distributed Processing 2.3.4 Classification by Processing...

Words: 26218 - Pages: 105

Free Essay

Informarion

...Mass media which regroup all the media apparatuses, for example, films, TV appears, informal communities, and so on has extraordinary impact on the general public, and particularly on youngsters (Srygley, 1978). As per Bandura's Social Cognitive Learning Theory individuals can learn practices and new contemplations if these four prerequisites are met which are consideration, memory, impersonation and wishes when the spectator is confronting any sort of practices in his surroundings that demonstrates the likelihood of taking in the showed conduct. Hence, any rough sort of conduct demonstrated can be obtained and learned through this standard. Consideration is an imperative component for observational taking in the individual ought to offer regard for any sort of model in the persona environment. At that point memory, once ought to remember the activity to impersonate the molecule activity and impersonation is one of the components as well. In conclusion, yearning is essential to inspire the once to impersonate the observational conduct. The inauspicious Bandura concentrates on Transmission of Aggression Through Imitation of Aggressive Models or Imitation of Film-Mediated Aggressive Models (Bandura,Ross, and Ross, 1961:1963), were set inside of a social learning idea and were planned to detect the procedures driving the ways that youngsters and adolescents learn by watching and impersonating the practices of others. In this connection, thusly, the studies utilized motivator films...

Words: 1169 - Pages: 5

Free Essay

Important

...philosophers and scientists with their descriptions AND write in the approximate year of their contribution. ______ Aristotle (______) 320 b.c. A. British philosopher, empiricist ______ Darwin (______) 360 b.c. B. Greek philosopher, nativist ______ Descartes (______) 1600 C. British biologist ______ Helmholz (______) 1700 D. German physiologist ______ Locke (______) 1830 E. French philosopher, nativist, and dualist ______ Plato (______) 1860 F. Greek philosopher, empiricist Pioneers of Psychology Match each of the pioneers of psychology with their descriptions AND write in the approximate year of their main contribution. ______ Calkins (______) 1879 A. Studied memory ______ Ebbinghaus (______) 1882 B. First psychotherapy ______ Freud (______) 1885 C. First lab in USA ______ Hall (______) 1888 D. Used introspection ______ James (______) 1890 E. First comprehensive textbook ______ Titchener (______) 1895 F. First psychology laboratory ______ Wundt (______) 1900 G. First woman president of APA Twentieth Century Psychology Match each of the key contributors with their descriptions AND write in the approximate year of their main contribution. ______ Chomsky (______) 1905 A. Studied learning in cats ______ Maslow (______) 1910 B. First woman...

Words: 7843 - Pages: 32