CELERON VS P4
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.
Tuesday, November 21, 2006
TYPES OF COMPUTER CASING
No, I couldn't believe it either, but after thinking about it for a while, I've come to the conclusion that this new machine is a good thing. It's good for the Sinclair brand, taking it into the nineties with a wry grin on its monitor. It's good for the user, presenting him or her wide a range of software unequalled by any other type of machine. And it's certainly good for Amstrad (who bought the Sinclair name in 1985, as it could make it the biggest manufacturer and seller of PCs in the world, and earn it a cow-choking wad of cash to boot. Yep, Alan Sugar is going to be positively surfing in money this time, if he isn't already.
So why a PC? At the risk of sounding like Barry Norman, why not? The world and his mum are buying PCs at the moment, so why shouldn't the Sinclair brand name be up there on the shelves among them? The PC compatible computer is an old concept, but it's a good one, and it has one big advantage - and any computer which has this goes on for years and years and years. And what's this advantage? Slots! No, I'm not being rude, I'm referring to the expansion slots inside the computer which take expansion cards (printed circuit boards which customise your computer to do any job you like - from being a satellite tracking station, to a Desk Top Publishing workstation or an arcade machine with advanced graphics). Okay that's the theory now for the practice!! The PC200The new Sinclair is a little black box, like all the other Sinclairs. Okay, it's a trifle larger than its predecessors but there are reasons for that. The computer's casing contains a 102 key keyboard, with proper typewriter keys in black and grey The top of the machine is slotted for ventilation, and although you could rest the monitor on top and still get the keyboard, it would probably break the top of the case. The matching monitor is designed to perch behind the machine and look over the back of it. Looking at the PC200 from the front, there's a disk drive built into the side of the case. Surprisingly, the drive's not of the usual Amstrad 3" type, but rather a standard Sony 3.5". There's a good reason for this, but I'll get onto that later. There are all the usual ports at the rear of the machine, RS232, Centronics printer, and an on/off switch (hoorah!), but interestingly for this class of computer, there's also a modulator socket for plugging into a TV set. Clean and simple lines, but a very powerful machine. Alright let's whip it apart. The DisplayThere are two different types of display. Either the CGA or MDA. Although this will mean something to converted PC users, it means nothing to the likes of me. Apparently all this yibbling means that CGA is the most popular graphics standard used by PC types. It's a 40 column x 25 line or 80 column x 25 line text in 16 colours, with 8 x 8 dot characters. Medium resolution graphics are 320 x 200 pixels in four colours, and high resolution is 640 x 200 with just two colours. MDA is a way of making your Sinclair outdo the Apple Macintosh in the monochrome stakes, with high definition 80 column x 25 line hi-res text, made up of 9 x 14 dot characters. Only the CGA mode is available through the TV modulator. The ProcessorThe machine runs on MS-DOS 3.3, supplied on disk, but it can run GEM 3 Desktop as well, for use with the mouse, to give you a modern windows, icons and pointers programming environment. The main processor es the popular 16 bit 8086, running at 8 Mhz, as used in the world-beating Amstrad line of PCs. (There is a socket for an 8087 maths co-processor too making it potentially a real number cruncher!) Yes, this is a proper 16 bit computer with 512K RAM as standard, but this is expandable using standard IBM or third party RAM cards. BIOS, the operating system of the computer, is resident in ROM, which means you don't have to load it from disk. The KeyboardThe stumbling block of most previous Sinclair computers has been their keyboards. Well, this is the Professional series, and in keeping with that image, the keyboard is the industry standard, full travel, AT keyboard (the AT is a type of IBM computer, in case you're wondering). The keys are tightly arranged on the compact casing, with the cursor keys, control and ALT keys, numeric keypad, and also a lot of IBM specific keys, like Page Up, Page Down, Home, Delete. Insert... all the usual stuff. Oh yes, and 10 function keys, too. The Caps Lock, Num Lock and Scroll Lock keys are equipped with green LEDs to show whether they're on or off. It's a nice keyboard, and believe it or not, you can actually use it for typing! The SoftwareWOW! There's games, if you want games. And although the software will not be Spectrum compatible, every major company is currently developing for the PC, and all new releases will have PC versions right up there with the other formats. There's a public domain library which will knock your eyes out. This is software written by programmers, hackers and enthusiasts which they don't charge for. It's free to anyone. And then there's the proper PC software. People have been programming this machine for about 8-10 years, and they know all about it. And better yet, programs for the PC run out at about 25 per cent cheaper than other types of computer. Because they can guarantee such high sales. You'll never run out of programs for this machine. Ever. The SlotsTwo IBM compatible slots, which can take any circuit board in the right format, one made by IBM, one made by a third party manufacturer, or even one made by your Uncle Fred with a soldering iron and a transistor radio. The range of things you can get to slot into a PC is quite staggering. Hard disks are available on cards, 20Meg models running out at about £300, you can even turn it into a fax machine by putting in a fax card! This is one feature which makes the PC future proof. If something comes along, like transputers for example, which revolutionise computing, you can slap it in the back of your Sinclair and off you go. Yes, you CAN get a transputer card to put in it! The DiskdriveA 3.5" drive is essential in this day and age. Fewer and fewer PCs have those clunky old 5.25" jobs, mostly because 3" disks have twice the storage capacity of their larger counterparts. You can add a supplementary 2.5" or 5.25" drive, which means that you can transfer programs from the small to large formats for carrying to work, college or school. One of the best things about owning this computer will be the fact that it's compatible with almost every other PC in the world? Yep, there are billions of them and the number is growing every day. It's like having a portable computer in every town in the world. The VerdictThere's a very bright future ahead for this line of computers. Anyone who wants a computer, for whatever reason, games, business, pleasure, or school, can take this machine and turn it into anything they want. It's solidly built, reliable, cheap to buy and cheap to run. There are three packages you can buy. The cheapest is just the computer to connect to your TV. With a mouse, GW-Basic, MS-DOS 3.3, GEM 3, and all the manuals, you can walk away with it for just £299 + VAT. With a mono monitor, joystick, a software package called Organiser and four games, it's £399 + VAT. Add a colour monitor instead of the mono job, and it's just £499 + VAT. I think it's a fine computer, and I want one. Now where did I throw that transputer card...?
The Sinclair PC200 Fax Box
8Mhz 8086 16 bit processor
512K RAM
Display adaptor running CGA (TV and monitor) and MDA (monitor only)
Built in TV modulator
Standard RS232 and Centronics ports
Built in power supply (hoo-ray!)
102-key AT style keyboard
Single 3.5" 720K disk drive
Expansion socket for additional drive
Speaker with volume control (yay!)
BIOS in ROM
Socket for 8087 maths co-processor
Two full size IBM expansion slots
Analog joystick port
Dimensions: 45cm x 8.5cm x 33.5cm
Weight: 5.4kg
Monitors: S-12MM mono monitor, 12", 7kg, 30.6cm x 28.9cm x 33.5cm; S-14CM colour monitor, 14", 10.35kg, 37cm x 35.5cm x 30.4cm
So why a PC? At the risk of sounding like Barry Norman, why not? The world and his mum are buying PCs at the moment, so why shouldn't the Sinclair brand name be up there on the shelves among them? The PC compatible computer is an old concept, but it's a good one, and it has one big advantage - and any computer which has this goes on for years and years and years. And what's this advantage? Slots! No, I'm not being rude, I'm referring to the expansion slots inside the computer which take expansion cards (printed circuit boards which customise your computer to do any job you like - from being a satellite tracking station, to a Desk Top Publishing workstation or an arcade machine with advanced graphics). Okay that's the theory now for the practice!! The PC200The new Sinclair is a little black box, like all the other Sinclairs. Okay, it's a trifle larger than its predecessors but there are reasons for that. The computer's casing contains a 102 key keyboard, with proper typewriter keys in black and grey The top of the machine is slotted for ventilation, and although you could rest the monitor on top and still get the keyboard, it would probably break the top of the case. The matching monitor is designed to perch behind the machine and look over the back of it. Looking at the PC200 from the front, there's a disk drive built into the side of the case. Surprisingly, the drive's not of the usual Amstrad 3" type, but rather a standard Sony 3.5". There's a good reason for this, but I'll get onto that later. There are all the usual ports at the rear of the machine, RS232, Centronics printer, and an on/off switch (hoorah!), but interestingly for this class of computer, there's also a modulator socket for plugging into a TV set. Clean and simple lines, but a very powerful machine. Alright let's whip it apart. The DisplayThere are two different types of display. Either the CGA or MDA. Although this will mean something to converted PC users, it means nothing to the likes of me. Apparently all this yibbling means that CGA is the most popular graphics standard used by PC types. It's a 40 column x 25 line or 80 column x 25 line text in 16 colours, with 8 x 8 dot characters. Medium resolution graphics are 320 x 200 pixels in four colours, and high resolution is 640 x 200 with just two colours. MDA is a way of making your Sinclair outdo the Apple Macintosh in the monochrome stakes, with high definition 80 column x 25 line hi-res text, made up of 9 x 14 dot characters. Only the CGA mode is available through the TV modulator. The ProcessorThe machine runs on MS-DOS 3.3, supplied on disk, but it can run GEM 3 Desktop as well, for use with the mouse, to give you a modern windows, icons and pointers programming environment. The main processor es the popular 16 bit 8086, running at 8 Mhz, as used in the world-beating Amstrad line of PCs. (There is a socket for an 8087 maths co-processor too making it potentially a real number cruncher!) Yes, this is a proper 16 bit computer with 512K RAM as standard, but this is expandable using standard IBM or third party RAM cards. BIOS, the operating system of the computer, is resident in ROM, which means you don't have to load it from disk. The KeyboardThe stumbling block of most previous Sinclair computers has been their keyboards. Well, this is the Professional series, and in keeping with that image, the keyboard is the industry standard, full travel, AT keyboard (the AT is a type of IBM computer, in case you're wondering). The keys are tightly arranged on the compact casing, with the cursor keys, control and ALT keys, numeric keypad, and also a lot of IBM specific keys, like Page Up, Page Down, Home, Delete. Insert... all the usual stuff. Oh yes, and 10 function keys, too. The Caps Lock, Num Lock and Scroll Lock keys are equipped with green LEDs to show whether they're on or off. It's a nice keyboard, and believe it or not, you can actually use it for typing! The SoftwareWOW! There's games, if you want games. And although the software will not be Spectrum compatible, every major company is currently developing for the PC, and all new releases will have PC versions right up there with the other formats. There's a public domain library which will knock your eyes out. This is software written by programmers, hackers and enthusiasts which they don't charge for. It's free to anyone. And then there's the proper PC software. People have been programming this machine for about 8-10 years, and they know all about it. And better yet, programs for the PC run out at about 25 per cent cheaper than other types of computer. Because they can guarantee such high sales. You'll never run out of programs for this machine. Ever. The SlotsTwo IBM compatible slots, which can take any circuit board in the right format, one made by IBM, one made by a third party manufacturer, or even one made by your Uncle Fred with a soldering iron and a transistor radio. The range of things you can get to slot into a PC is quite staggering. Hard disks are available on cards, 20Meg models running out at about £300, you can even turn it into a fax machine by putting in a fax card! This is one feature which makes the PC future proof. If something comes along, like transputers for example, which revolutionise computing, you can slap it in the back of your Sinclair and off you go. Yes, you CAN get a transputer card to put in it! The DiskdriveA 3.5" drive is essential in this day and age. Fewer and fewer PCs have those clunky old 5.25" jobs, mostly because 3" disks have twice the storage capacity of their larger counterparts. You can add a supplementary 2.5" or 5.25" drive, which means that you can transfer programs from the small to large formats for carrying to work, college or school. One of the best things about owning this computer will be the fact that it's compatible with almost every other PC in the world? Yep, there are billions of them and the number is growing every day. It's like having a portable computer in every town in the world. The VerdictThere's a very bright future ahead for this line of computers. Anyone who wants a computer, for whatever reason, games, business, pleasure, or school, can take this machine and turn it into anything they want. It's solidly built, reliable, cheap to buy and cheap to run. There are three packages you can buy. The cheapest is just the computer to connect to your TV. With a mouse, GW-Basic, MS-DOS 3.3, GEM 3, and all the manuals, you can walk away with it for just £299 + VAT. With a mono monitor, joystick, a software package called Organiser and four games, it's £399 + VAT. Add a colour monitor instead of the mono job, and it's just £499 + VAT. I think it's a fine computer, and I want one. Now where did I throw that transputer card...?
The Sinclair PC200 Fax Box
8Mhz 8086 16 bit processor
512K RAM
Display adaptor running CGA (TV and monitor) and MDA (monitor only)
Built in TV modulator
Standard RS232 and Centronics ports
Built in power supply (hoo-ray!)
102-key AT style keyboard
Single 3.5" 720K disk drive
Expansion socket for additional drive
Speaker with volume control (yay!)
BIOS in ROM
Socket for 8087 maths co-processor
Two full size IBM expansion slots
Analog joystick port
Dimensions: 45cm x 8.5cm x 33.5cm
Weight: 5.4kg
Monitors: S-12MM mono monitor, 12", 7kg, 30.6cm x 28.9cm x 33.5cm; S-14CM colour monitor, 14", 10.35kg, 37cm x 35.5cm x 30.4cm
1394 firewire
1394-Firewire
1394 / Firewire / i.Link im Detail
Bei Apple-Computern und Sony-Notebooks ist 1394 alias Firewire oder i.Link längst Standard. Jetzt setzt die schnelle serielle Schnittstelle auch im PC-Bereich zum Überholen an. tecChannel hat die1394-Schnittstelle analysiert und nennt Ihnen die Vor- und Nachteile sowie die Unterschiede der diversen Implementierungen.
VON MICHAEL ECKERT
Von gestern und doch hochaktuell - 1394 ist ein schnelles Interface, das alle anderen Peripherie- und Massenspeicher-Schnittstellen verdrängen soll. Dabei hat Apple mit der Entwicklung dieses seriellen Anschlusses schon 1986 begonnen. Die Ingenieure übernahmen den seriellen Bus IEEE 1394. Dieser war zu der Zeit noch nicht als endgültiger Standard verabschiedet und ursprünglich nur als Diagnosebus in parallelen Backplane-Bussen gedacht. 1993 demonstrierte Apple die Weiterentwicklung unter dem Namen Firewire, die später als IEEE 1394-1995 standardisiert wurde.
TYPES of POWER SUPPLY
POWER SUPPLY
A power supply (sometimes known as a power supply unit or PSU) is a device or system that supplies electrical or other types of energy to an output load or group of loads. The term is most commonly applied to electrical energy supplies.
General description
The complete range of power supplies is very broad, and could be considered to include all forms of energy conversion from one form into another. Conventionally though, the term is usually confined to electrical or mechanical energy supplies. Constraints that commonly affect power supplies are the amount of power they can supply, how long they can supply it for without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulses.
The regulation of power supplies is done by incorporating circuitry to tightly control the output voltage and/or current of the power supply to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply's output, or any reasonable voltage variation at the power supply's input. This kind of regulation is commonly categorised as a Stabilized power supply.
Electrical power supplies
This term covers the mains power distribution system together with any other primary or secondary sources of energy such as:
- Conversion of one form of electrical power to another desired form and voltage. This typically involves converting 120 or 240 volt AC supplied by a utility company (see electricity generation) to a well-regulated lower voltage DC for electronic devices. For examples, see switched-mode power supply, linear regulator, rectifier and inverter (electrical).
- Batteries
- Chemical fuel cells and other forms of energy storage systems
- Solar power
- Generators or alternators (particularly useful in vehicles of all shapes and sizes, where the engine has rotational power to spare, or in semi-portable units containing an internal combustion engine and a generator) (For large-scale power supplies, see electricity generation.) Low voltage, low power DC power supply units are commonly integrated with the devices they supply, such as computers and household electronics.
Computer power supply
Main article: Computer power supply
A computer power supply typically is designed to convert 110 V or 230 V AC power from the mains to usable low-voltage DC power for the internal components of the computer. The most common computer power supplies are built to conform with the ATX form factor.
Domestic mains adaptors
A power supply (or in some cases just a transformer) that is built into the top of a plug is known as a wall wart, power brick, plug-in adapter or just power adapter. Because they consume Standby power, they are sometimes known as electricity vampires.
Linear power supply
A simple AC powered linear power supply usually uses a transformer to convert the voltage from the wall outlet (mains) to a different, usually a lower voltage. If it is used to produce DC a rectifier circuit is employed either as a single chip, an array of diodes sometimes called a diode bridge both for fullwave rectification or a single diode yielding a half wave (pulsating) output. More elaborate configurations rectify the AC voltage at first to pulsating DC. Then a capacitor smooths out part of the pulses giving a type of DC voltage. The smaller pulses remaining are known as ripple. Because of a fullwave rectification they occur at twice the mains frequency (in
In the simplest case a single diode is connected directly to the mains and uses a resistor in series with a more or less fixed load to recharge a battery. This circuit is common in rechargeable flashlights.
Switched-mode power supply
In a switched-mode power supply the incoming power is passed through a transistor and transformer network that switches on and off at typical rates of 10 kHz to 1 MHz. The original design was invented by Dr Gary Bocock in 1965 often referred to as the father of power conversion. This means that a smaller, less expensive, lighter transformer can be used, because the voltage is being made to alternate faster, and thus a smaller magnetic core can be used. The switch mode PSU is also significantly more efficient than the linear design. Typically 80 - 90% compared to 50 - 60%. The downside to this design is that the switching on and off at high speeds introduces electrical noise into the system which can cause interference with the power supply load or other connected systems.
Switching power supplies can be used as DC to DC converters. In this application, the power supply is designed to accept a limited range DC input and then output a different DC voltage. This is particularly useful in portable devices, as well as power distribution in large electronic equipment. A transformerless switching power supply that outputs a voltage higher than its input voltage is typically called a boost converter. A transformerless switching power supply that outputs a voltage lower than its input voltage is typically called a buck converter. These transformerless switching power supplies use an inductor as the primary circuit element in converting the voltage. Circuitry is used to pass current through the inductor to store a certain amount of electrical energy as a magnetic field. The current flow is then stopped, and the magnetic field collapses causing the stored energy to be released as current again. This is done rapidly (up to millions of times per second). By carefully metering the amount of energy stored in the inductor, the current released by the inductor can be regulated thus allowing the output voltage to be tightly regulated. A switching power supply incorporating a transformer can provide many output voltages simultaneously, and is typically called a flyback converter. Switching power supplies are typically very efficient if well designed, and therefore waste very little power as heat. Because of these efficiencies, they are typically much smaller and lighter than an equivalently rated linear supply.
Power conversion
The term "power supply" is sometimes restricted to those devices that convert some other form of energy into electricity (such as solar power and fuel cells and generators). A more accurate term for devices that convert one form of electric power into another form of electric power (such as transformers and linear regulators) is power converter.
Uses in aviation
The most exotic power supplies are used in aviation to enable reliable restarting of stalled engines.
In jet transports, an engine is restarted using power produced by 400 Hz three-phase AC generator(s) attached to the shaft(s) of the other engine(s). Most of the starting torque generated by the engine's motor/generator is provided by the current at the peaks of the AC waveform.
If the aircraft electronics used simple rectifying power supplies, they would use current only from these peaks, since the diodes conduct only during voltage peaks where input voltage is higher than output voltage. This could prevent the pilot from restarting an engine in an emergency.
Therefore, aircraft power supplies take energy evenly from all parts of the AC waveform. This uses a switching power supply technique called "power factor correction," which creates a balanced current draw over the entire AC waveform.
Mechanical power supplies
- Flywheels coupled to electrical generators or alternators
- Compulsators
- Explosively pumped flux compression generators
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