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Showing posts from May, 2009

OSI model

Introduction The Open Systems Interconnection (OSI) model is a reference tool for understanding data communications between any two networked systems. It divides the communications processes into seven layers. Each layer both performs specific functions to support the layers above it and offers services to the layers below it. The three lowest layers focus on passing traffic through the network to an end system. The top four layers come into play in the end system to complete the process. An Overview of the OSI Model --> A networking model offers a generic means to separate computer networking functions into multiple layers. Each of these layers relies on the layers below it to provide supporting capabilities and performs support to the layers above it. Such a model of layered functionality is also called a “protocol stack” or “protocol suite”. Protocols, or rules, can do their work in either hardware or software or, as with most protocol stacks, in a combinat

Speed up Mac OS X Leopard

After a year and a half of running Mac OS X Snow Leopard things have become extraordinarily slow on my MacBook Pro. After a quick googling on the subject of how to speed up Mac OS X Leopard I have decided to write my own brief tutorial on a handful of things you can do to effectively increase the performance of OS X. This is meant as a programmer’s quick reference guide so if you are not technically savvy you may want to google “performance tune mac os x” for more verbose explanations. 13 Mac Performance Tuning Applications and Tips Run the Mac OS X disk repair utility location in Applications > Utilities > Disk Utility and then run repair disk permissions. See this article on the repair functions of the disk utility. Download and run Monolingual to remove all the additional languages that are built into OS X by default and you are likely to never use. I removed everything except English, Spanish, German and French since those are core languag

Network topology

Physical topologies The mapping of the nodes of a network and the physical connections between them – i.e., the layout of wiring, cables, the locations of nodes, and the interconnections between the nodes and the cabling or wiring system [ Classification of physical topologies Point-to-point The simplest topology is a permanent link between two endpoints (the line in the illustration above). Switched point-to-point topologies are the basic model of conventional telephony. The value of a permanent point-to-point network is the value of guaranteed, or nearly so, communications between the two endpoints. The value of an on-demand point-to-point connection is proportional to the number of potential pairs of subscribers, and has been expressed as Metcalfe's Law. Permanent (dedicated) Easiest to understand, of the variations of point-to-point topology, is a point-to-point communications channel that appears, to the user, to be permanently associated with the two endpoints.

Creating an Automated Install of WindowsXP

On the WindowsXP CP, in the SUPPORT\TOOLS directory, there is a file called DEPLOY.CAB. Extract the programs DEPLOY.CHM (help file) and SETUPMGR.EXE (main program) Run SETUPMGR and answer the prompts. This will create both a unattend.bat and unattend.txt file you can use for automated installs. Note: The batch file might need some minor modification for file locations but it is fairly basic.

Decreasing Boot Time

Microsoft has made available a program to analyze and decrease the time it takes to boot to WindowsXP The program is called BootVis Uncompress the file. Run BOOTVIS.EXE For a starting point, run Trace / Next Boot + Driver Delays This will reboot your computer and provide a benchmark After the reboot, BootVis will take a minute or two to show graphs of your system startup. Note how much time it takes for your system to load (click on the red vertical line) Then run Trace / Optimize System Re-Run the Next Boot + Drive Delays Note how much the time has decreased Mine went from approximately 39 to 30 seconds.

Clearing the Page File on Shutdown

Another way to set the computer to clear the pagefile without directly editing the registry is: Click on the Start button Go to the Control Panel Administrative Tools Local Security Policy Local Policies Click on Security Options Right hand menu - right click on "Shutdown: Clear Virtual Memory Pagefile" Select "Enable" Reboot If you want to clear the page file on each shutdown: Start Regedit Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\ClearPageFileAtShutdown Set the value to 1

Windows Page file

Windows Page file is the biggest file in terms of space occupied. It doesn't show any icons of itself even the folder option settings are set to 'Show All Files'. It is configured as a hidden file by Microsoft itself. It contains Virtual Memory file which is to manage the RAM and speed of the computer. This file is situated at /Control Panel/System/Performance/Virtual Memory (You can open it by right clicking on your 'My Computer' icon. Here the default option is 'Let Windows manage my Virtual Memory settings'. Change it to 'Let me specify my own Virtual Memory settings'. The amount of hard disk (min & max) space should not be more than 2.5 times the RAM. Better to chose the double space than RAM. The minimum value should be the same as the RAM. Restart the computer and see the difference.

Computer Beep Codes Manual

Computer Beep Codes Manual Beep Code Manual, Better Than Gold Techies, American Megatrends Int. & Phoenix BIOS Beep Codes When a computer is first turned on, or rebooted, its BIOS performs a power-on self test (POST) to test the system's hardware, checking to make sure that all of the system's hardware components are working properly. Under normal circumstances, the POST will display an error message; however, if the BIOS detects an error before it can access the video card, or if there is a problem with the video card, it will produce a series of beeps, and the pattern of the beeps indicates what kind of problem the BIOS has detected. Because there are many brands of BIOS, there are no standard beep codes for every BIOS. The two most-used brands are AMI (American Megatrends International) and Phoenix . Below are listed the beep codes for AMI systems, and here are the beep codes for Phoenix AMI Beep Codes Beep Code Meaning 1 beep DRAM refresh failu