Introduction
In the previous lessons, we learned different techniques of creating and manipulating text. The problem is that we didn't preserve that text and, either when we closed the application or shut down the computer, all our valuable work was gone. Most of the time, after creating something using an application, you may want to keep it for later reference. You may even want to give or send it to someone else.
File processing consists of creating something on a computer and keeping it. The thing you keep is called information or datum. The plural of datum is data. In some cases, the word data can be used in both singular and plural forms. There are various issues related and different techniques used to keep data.
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A medium is an object used to hold information in a computer. The plural of medium is media. There are various kinds of them.
Internal Hard Drives
The primary object used to hold information in a computer is called the hard drive:
Everything (data) in your computer is stored in the hard drive. The hard drive is a rectangular box that contains some discs and other parts. The information stored in a hard drive is written on its discs. The information can be written to, erased from, copied or moved among discs. Although you will perform these operations, the operating system is in charge of deciding how the operations are carried out inside. You will not need to know what is going on inside.
The hard drive is inside of the computer, connected to another wide flat object called the motherboard, using cables. This type of hard drive is referred to as internal and this the most classic type.
When you purchase a computer, it already has a hard drive. Later on, if you know about computers and you have some complaints about your hard drive, you can either add a second one to your computer or you can replace the hard drive in your computer.
External Hard Drives
Until recently, the hard drive was traditionnally thought of as a piece of hardware inside the computer. For this reason, it couldn't be carried away easily: you had to open the computer, disconnect the cables, and then remove the hard drive. Even then, some other issues were related (such as the type of cable, etc) so much that people were not in the habit of carrying a hard drive from one computer to another. Fortunately, another technology was developped.
Another type of hard drive stays outside of the computer and it is referred to as external. Here are examples:
An external hard drive is usually connected to the computer using a cable to a port (USB) outside the computer. What makes it valuable is that, by simply disconnecing its cable, an external hard drive can easily be carried from one computer to another. And because the external hard drive doesn't have the same particularities of cables (IDE vs SATA), it can easily be connected to almost any common computer (PC).
To use a hard drive, there is no particular action you must perform. When we get to the issues of storing data, we willl see that you don't need to know what the hard drive does; you simply know and confidently believe that it's doing its job.
If you purchase a computer, you usually don't get it with an external drive. If you need one, you can acquire it, either from purchase or getting it from somebody. The external hard drive is fairly easy to install. You primarily connect a (USB) cable from the back of the hard drive to a (USB) port on the computer. In most cases, it should be ready to install (Plug n' Play) or it may quickly install the software (driver) it needs to function. In some cases, after inserting the cable and turning the device on, a window may come up asking you to install something (a driver), which you would also have received from the manufacturer.
Another type of hard drive stays outside of the computer and it is referred to as external. Here are examples:
An external hard drive is usually connected to the computer using a cable to a port (USB) outside the computer. What makes it valuable is that, by simply disconnecing its cable, an external hard drive can easily be carried from one computer to another. And because the external hard drive doesn't have the same particularities of cables (IDE vs SATA), it can easily be connected to almost any common computer (PC).To use a hard drive, there is no particular action you must perform. When we get to the issues of storing data, we willl see that you don't need to know what the hard drive does; you simply know and confidently believe that it's doing its job.
If you purchase a computer, you usually don't get it with an external drive. If you need one, you can acquire it, either from purchase or getting it from somebody. The external hard drive is fairly easy to install. You primarily connect a (USB) cable from the back of the hard drive to a (USB) port on the computer. In most cases, it should be ready to install (Plug n' Play) or it may quickly install the software (driver) it needs to function. In some cases, after inserting the cable and turning the device on, a window may come up asking you to install something (a driver), which you would also have received from the manufacturer.
4, 8, 12, 16 Channel DVR Servers
Program at Glance: * Site Server at Glance* Record Player at Glance* Backup Scheduler at Glance* Remote Viewer at Glance* Remote Record Player at Glance* PDA Remote at GlanceThe new High Speed (60frames per second) DVR servers comes with 4, 8,16 channel video and 1 channel audio inputs. It gives you Superb Digital Images from Multiple Cameras and Remote Surveillance that eliminates the need for multiplexers and Recorders. Our system stores your recordings in highly compressed MPEG4 files format (1 week /7GB recording).Imagine not having to watch endless hours of recordings of nothing and be able to choose motion activated video capture only. Our surveillance system can alert you by email, or phone to alert you motion has activated the secured area. And be alerted that the area has been violated. THE TECHNOLOGY IS HERE... IT IS SIMPLE TO INSTALL AND VERY AFFORDABLEREPLACE OUTDATED MULTIPLEXERS & TIME LAPSE RECORDERS WITH STATE OF THE ART DIGITAL COMPUTER STORAGE. DIGITAL MULTIPLEX RECORDING ON DVR SERVER HARD DRIVE.
Features and Specifications: • Inpute Signal - 4 Video, 1 audio input (with Sound Card) • Display fps – 30 to 120 fps/NTSC per card • Record fps 30 to 120 fps/NTSC per card • Display Screen 1 / 4 Full Screen • Audio Input 1 Synchronized Mono (from Sound Card) • Color Adjust - Adjustable Light, Contrast, Hue, Saturation by Individual Camera • Resolution - 160X120 / 240X180 / 320X240 / 352X288 / 480X360 / 640X480 • Record Mode Event - Continuous / Schedule Recording • Compression - Special MPEG4 Format, Frame Size: .1K~2.5K, 1200hr~4000hr / 80GB • Audio - One Channel using Sound Card • Multi-task - Monitoring / Recording / PTZ Control / Remote / Backup • Motion Detection - 16 Zone X Multi Area for each camera • Storage - HDD / VDRAM / CD-RW / DAT / MO / ZIP / RAID. Up to 24 drives • PTZ - RS422 ? RS485 Controlled PTZ & Light / Power / Wiper • Playback Speed - Forward / Back / Step / Fast / Slow • Schedule - Forward / Back / Step / Fast / Slow • Password - System / Playback / Remote Users • System Requirement: O.S. - Windows 2000/XP Remote View: • IP Multicast (LAN) • Remote View (TCP/IP, ISDN,PSTN, Intranet, Internet) • GeoCenter (TCP/IP, Intranet / Internet) • Built-in Web Browser (HTTP) • Remote recording allowed • Remote zoom-in / zoom-out allowed Storage of Video Data: • Log File back up to HDD, MO, CD-ROM, .zip, or remote backup through LAN • Log File management for each camera with Year, Date, Time information • Log File playback with zoom-in / zoom-out • Log File prints in single frame (like photo) Camera Management: • Individual camera configuration, naming, video quality • Sequential scan among cameras • Send alarm when camera lost signal
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