Wednesday, November 22, 2006

cpu sockets

The term CPU socket (or CPU slot) is widely used to describe the connector linking the motherboard to the CPU(s) in certain types of desktop and server computers, particularly those compatible with the Intel x86 architecture.
Most CPU sockets and processors in use today are built around the pin grid array (PGA) architecture, in which the pins on the underside of the processor are inserted into the socket, usually with zero insertion force (ZIF) to aid installation. In contrast to this, several current and upcoming sockets use a land grid array (LGA) in which the pins are on the socket side instead and come in contact with pads on the processor. Slot based processors are cartridge shaped and fix into a slot that looks similar to expansion slots

Wednesday, November 15, 2006

types of computer casing

Abstract:
The portable computer has a computer casing provided with a rectangular receiving space accessible from one side thereof, and a socket connector projecting inwardly into the receiving space from an innermost end of the receiving space and being electrically connected to the internal circuitry confined by the computer casing. A detachable cartridge type interface device has a rectangular casing detachably provided in the receiving space of the computer casing, and an interface card confined inside the rectangular casing. The rectangular casing has a rear end provided with a rectangular opening to access one end of the interface card. The socket connector extends into the rectangular opening to engage the interface card so as to electrically connect the same to the internal circuitry. The front end of the rectangular casing is provided with a socket to permit electrical connection of the portable compute with an external device.

Types of power supply

Power Supply Types
Types of Power Supplies
Three primary types of power supplies are used for laptops: ac adapters, dc adapters and inverters. Each is different in what it does, and the selection of the appropriate one is dictated by the nature of the power supply that is available for use.Laptop Travel carries a complete line of laptop power adapters, AC, auto and auto/air adapters, for Apple, Compaq, Dell, Gateway, HP, IBM, Sony, Toshiba and many other laptop and notebook brands. Click here to select your laptop model from the drop down menu for a list of avaliable power supplies and power adapters for your laptop. See below for more information about each type of power supply.
AC and DC Power
Laptops, many printers and other computer peripherals require direct current (DC) electricity. DC power is produced by batteries and occurs in nature in static or lightning, but it is not the type of power that is generally available in home and office electric outlets. These generally provide alternating current (AC) electricity, the type used by most household appliances.
AC Adapters
Laptops and other DC devices generally have two common characteristics: the ability of the device to run on batteries and the presence of a small power “brick” outside the device that powers it. They cannot be used with AC power unless the power is “converted” before use. Their power "bricks" are really DC power supplies that convert the AC power from the wall socket into the DC power required for the device. They are often called AC Adapters or chargers (because of their function of charging the internal laptop battery), and have an electric plug for the wall socket on one end and a special connector for plugging into the laptop or other device on the other end.
DC Adapters
Auto batteries, in-flight power systems and solar power systems are common sources of DC power. Although they produce the DC power used by laptops and other DC power devices, they generally produce voltage that is below what is required by many such DC devices. (For example auto batteries usually produce 12V, which is below the voltage required by most laptops.) Thus DC adapters are necessary to adapt the voltage coming from the power source to the voltage that is required by the laptop or other DC device. They have a DC input plug such as a cigarette lighter plug on one end and a special connector for plugging into the laptop or other device on the other end.
Inverters
Inverters are used to change DC power into AC power for use by all electric appliances and electronics. This is generally done by plugging the inverter into the DC source (typically a cigarette lighter receptacle) and providing in the body of the inverter one or more standard household electric sockets. The advantage of an inverter is that it can be used to provide power for ANY device because it is basically supplying a standard AC socket. The disadvantages of an inverter are that the power conversion process is not as efficient as the DC adapter process and that as a rule inverters are larger and heavier than DC adapters.

1394-firewire

FireWire is a proprietary name of Apple Computer for the IEEE 1394 interface. It is also known as i.Link or IEEE 1394 (although the 1394 standard also defines a backplane interface). It is a personal computer (and digital audio/digital video) serial bus interface standard, offering high-speed communications and isochronous real-time data services. FireWire has replaced Parallel SCSI in many applications due to lower implementation costs and a simplified, more adaptable cabling system. IEEE 1394 has been adopted as the High Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V component communication and control.
Almost all modern digital camcorders have included this connection since 1995. Many computers intended for home or professional audio/video use have built-in FireWire ports including all Apple, Dell and Sony laptop computers currently produced. FireWire was also an attractive feature on the Apple iPod for several years, permitting new tracks to be uploaded in a few seconds and also for the battery to be recharged concurrently with one cable. However, Apple has eliminated FireWire support in favor of USB on its newer iPods due to space constraints and for wider compatibility.
Contents[hide]
1 History and development
2 Technical specifications
2.1 Operating system support
2.2 Node hierarchy
3 Standards and versions
3.1 FireWire 400
3.2 FireWire 800
4 Networking over FireWire
5 Security issues
6 Precautions
6.1 Hot Plug precautions
7 See also
8 References
9 External links
//

[edit] History and development

A 6-Pin FireWire 400 connector
FireWire is Apple Computer's name for the IEEE 1394 High Speed Serial Bus. It was initiated by Apple and developed by the IEEE P1394 Working Group, largely driven by contributors from Apple, although major contributions were also made by engineers from Texas Instruments, Sony, Digital Equipment Corporation, IBM, and SGS Thomson (now STMicroelectronics).
Apple intended FireWire to be a serial replacement for the parallel SCSI bus while also providing connectivity for digital audio and video equipment. Apple's development was completed in 1995. As of 2006, IEEE 1394 is currently a composite of three documents: the original IEEE Std. 1394-1995, the IEEE Std. 1394a-2000 amendment, and the IEEE Std. 1394b-2002 amendment (there is a 1394c amendment that provides support for 800 Mbit/sec operation over 100 m of Category 5 unshielded twisted pair cable that will be published soon).
Sony's implementation of the system is known as i.Link, and uses only the four signal pins, discarding the two pins that provide power to the device in favor of a separate power connector on Sony's i.Link products.
The system is commonly used for connection of data storage devices and digital video cameras, but is also popular in industrial systems for machine vision and professional audio systems. It is used instead of the more common USB due to its faster effective speed, higher power-distribution capabilities, and because it does not need a computer host. Perhaps more importantly, FireWire makes full use of all SCSI capabilities and, compared to USB 2.0 High Speed, has higher sustained data transfer rates, a feature especially important for audio and video editors.
However, the small royalty that Apple Computer and other patent holders have initially demanded from users of FireWire (US$0.25 per end-user system) and the more expensive hardware needed to implement it (US$1–$2) has prevented FireWire from displacing USB in low-end mass-market computer peripherals where cost of product is a major constraint.
According to Michael Johas Teener, original chair and editor of the IEEE 1394 standards document, and technical lead for Apple's FireWire team from 1990 until 1996:[citation needed]

The original FireWire project name was "Chefcat", the name of Michael Teener's favorite coffee cup. The standard connectors used for FireWire are related to the connectors on the venerable Nintendo Game Boy. While not especially glamorous, the Game Boy connectors have proven reliable, solid, easy to use and immune to assault by small children.
FireWire is a trademark of Apple Computer, Inc. The trademark was filed in 1993. The "FireWire" name was chosen by a group of engineers socializing before Comdex 1993, just before the project was about to go public. IBM, Apple, Texas Instruments, Western Digital, Maxtor and Seagate were all showing drives, systems and other various FireWire support technology. The marketing forces behind the FireWire project had originally considered a name like "Performa".
FireWire won the "most significant new technology" award from Byte Magazine at the Comdex 1993 show.
During the period they participated with the IEEE p1394 working group, Apple proposed licensing all of their blocking patents for US$3,000, a one time fee only for "the point of first use" or the integrated circuits that implement the protocols. Furthermore, there was a discount if a contribution was made to the IEEE undergraduate scholarship fund. Under that agreement, the IEEE agreed to include the appropriate patents in the standard.
Apple never intended to charge for the use of the name "FireWire". It could be used by any party signing an agreement to use the name for a product that was compliant with IEEE 1394-1995, the original version of the standard. Steve Jobs was convinced that Apple should ask for US$1 per port for the patents that became part of the standard. The argument was that it was consistent with the MPEG patent fees.
The fallout from charging US$1 per FireWire port was significant, particularly from Intel. Intel had sunk a great deal of effort into the standard with the improved 1394a-2000 standard being partially based on work contributed by Intel. A group within Intel used this as a reason to drop 1394 support and bring out the improved USB 2.0 instead.
Simultaneously, Sony and the other backers of the technology noted to Apple that they all had patents too and were entitled to per-port royalties. Under these circumstances, Apple would have to pay roughly US$15 per port to the other FireWire technology developers. The end result was the creation of the "1394 Licensing Authority", a body which charges everyone US$0.25 per end-user system (like a car or computer) that uses any 1394 technology

celeron vs. pentium 4

The Celeron and Pentium Processors are two of Intel's best selling CPUs. They are found in a majority of home computer systems. When comparing the two processors it should be first understood that there are different types of Pentium processors - the original Pentium all the way to the Pentium 4 (the latest Pentium processor). The Celeron processors are more or less the same, although you will find them in a wide variety of speeds.
The Intel Celeron processor was always designed to be a low-cost alternative to the Pentium processor line. It is much like a car company that offers various priced cars from the luxury sedan to the economy compact. The Celeron is simply a downgraded Pentium, that almost anyone can afford (it is essentially the compact). To begin, Celeron chips have a smaller L2 cache 9128kb compared with 512kb in the Pentium 4 Northwood, which translates into slower processing speeds. In fact, current Celerons have a clock speed limit of about 2.0GHz, where as the Pentium for is capable of speed in excess of 3.0GHz. In addition, the Pentium runs at a lower core voltage because it is more energy effecient (1.75V vs. 1.5V).
In summary, the Pentium 4 is more powerful than the most advanced Celeron processor on the market. However, Intel has planned it to be this way. Many applications will work just great with a Celeron processor, despite a little less power than the Pentium 4. It is a way to save a little cash when buying a new pc - but don't forget the saying "you get what you pay for." Celeron processors are of good Intel quality, but they will never be as good as the Pentium.
This Celeron vs. Pentium review was brought to you by SciNet Science and Technology Search Engine. SciNet is not affiliated with or specifically endorses the Celeron or Pentium processors or the manufacturer, Intel Corp. Please consult the Celeron and Pentium product information and configuration before you purchase either processor. It is also a good idea to seek other up-to-date product reviews and information as necessary.