by Marshall Brain
The Base-2 System and the 8-bit Byte
The reason computers use the base-2 system is because it makes it a lot easier to implement them with current electronic technology. You could wire up and build computers that operate in base-10, but they would be fiendishly expensive right now. On the other hand, base-2 computers are relatively cheap.
So computers use binary numbers, and therefore use binary digits in place of decimal digits. The word bit is a shortening of the words "Binary digIT." Whereas decimal digits have 10 possible values ranging from 0 to 9, bits have only two possible values: 0 and 1. Therefore, a binary number is composed of only 0s and 1s, like this: 1011. How do you figure out what the value of the binary number 1011 is? You do it in the same way we did it above for 6357, but you use a base of 2 instead of a base of 10. So:
(1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (1 * 2^0) = 8 + 0 + 2 + 1 = 11
You can see that in binary numbers, each bit holds the value of increasing powers of 2. That makes counting in binary pretty easy. Starting at zero and going through 20, counting in decimal and binary looks like this:
0 = 0
1 = 1
2 = 10
3 = 11
4 = 100
5 = 101
6 = 110
7 = 111
8 = 1000
9 = 1001
10 = 1010
11 = 1011
12 = 1100
13 = 1101
14 = 1110
15 = 1111
16 = 10000
17 = 10001
18 = 10010
19 = 10011
20 = 10100
When you look at this sequence, 0 and 1 are the same for decimal and binary number systems. At the number 2, you see carrying first take place in the binary system. If a bit is 1, and you add 1 to it, the bit becomes 0 and the next bit becomes 1. In the transition from 15 to 16 this effect rolls over through 4 bits, turning 1111 into 10000.
Bits are rarely seen alone in computers. They are almost always bundled together into 8-bit collections, and these collections are called bytes. Why are there 8 bits in a byte? A similar question is, "Why are there 12 eggs in a dozen?" The 8-bit byte is something that people settled on through trial and error over the past 50 years.
With 8 bits in a byte, you can represent 256 values ranging from 0 to 255, as shown here:
0 = 00000000
1 = 00000001
2 = 00000010
...
254 = 11111110
255 = 11111111
In the article How CDs Work, you learn that a CD uses 2 bytes, or 16 bits, per sample. That gives each sample a range from 0 to 65,535, like this:
0 = 0000000000000000
1 = 0000000000000001
2 = 0000000000000010
...
65534 = 1111111111111110
65535 = 1111111111111111
Next, we'll look at one way that bytes are used.
Monday, January 28, 2008
How Bits and Bytes Work (Introduction)
by Marshall Brain
Introduction to How Bits and Bytes Work
If you have used a computer for more than five minutes, then you have heard the words bits and bytes. Both RAM and hard disk capacities are measured in bytes, as are file sizes when you examine them in a file viewer.
You might hear an advertisement that says, "This computer has a 32-bit Pentium processor with 64 megabytes of RAM and 2.1 gigabytes of hard disk space." And many HowStuffWorks articles talk about bytes (for example, How CDs Work). In this article, we will discuss bits and bytes so that you have a complete understanding.
Decimal Numbers
The easiest way to understand bits is to compare them to something you know: digits. A digit is a single place that can hold numerical values between 0 and 9. Digits are normally combined together in groups to create larger numbers. For example, 6,357 has four digits. It is understood that in the number 6,357, the 7 is filling the "1s place," while the 5 is filling the 10s place, the 3 is filling the 100s place and the 6 is filling the 1,000s place. So you could express things this way if you wanted to be explicit:
(6 * 1000) + (3 * 100) + (5 * 10) + (7 * 1) = 6000 + 300 + 50 + 7 = 6357
Another way to express it would be to use powers of 10. Assuming that we are going to represent the concept of "raised to the power of" with the "^" symbol (so "10 squared" is written as "10^2"), another way to express it is like this:
(6 * 10^3) + (3 * 10^2) + (5 * 10^1) + (7 * 10^0) = 6000 + 300 + 50 + 7 = 6357
What you can see from this expression is that each digit is a placeholder for the next higher power of 10, starting in the first digit with 10 raised to the power of zero.
That should all feel pretty comfortable -- we work with decimal digits every day. The neat thing about number systems is that there is nothing that forces you to have 10 different values in a digit. Our base-10 number system likely grew up because we have 10 fingers, but if we happened to evolve to have eight fingers instead, we would probably have a base-8 number system. You can have base-anything number systems. In fact, there are lots of good reasons to use different bases in different situations.
Computers happen to operate using the base-2 number system, also known as the binary number system (just like the base-10 number system is known as the decimal number system). Find out why and how that works in the next section.
Introduction to How Bits and Bytes Work
If you have used a computer for more than five minutes, then you have heard the words bits and bytes. Both RAM and hard disk capacities are measured in bytes, as are file sizes when you examine them in a file viewer.
You might hear an advertisement that says, "This computer has a 32-bit Pentium processor with 64 megabytes of RAM and 2.1 gigabytes of hard disk space." And many HowStuffWorks articles talk about bytes (for example, How CDs Work). In this article, we will discuss bits and bytes so that you have a complete understanding.
Decimal Numbers
The easiest way to understand bits is to compare them to something you know: digits. A digit is a single place that can hold numerical values between 0 and 9. Digits are normally combined together in groups to create larger numbers. For example, 6,357 has four digits. It is understood that in the number 6,357, the 7 is filling the "1s place," while the 5 is filling the 10s place, the 3 is filling the 100s place and the 6 is filling the 1,000s place. So you could express things this way if you wanted to be explicit:
(6 * 1000) + (3 * 100) + (5 * 10) + (7 * 1) = 6000 + 300 + 50 + 7 = 6357
Another way to express it would be to use powers of 10. Assuming that we are going to represent the concept of "raised to the power of" with the "^" symbol (so "10 squared" is written as "10^2"), another way to express it is like this:
(6 * 10^3) + (3 * 10^2) + (5 * 10^1) + (7 * 10^0) = 6000 + 300 + 50 + 7 = 6357
What you can see from this expression is that each digit is a placeholder for the next higher power of 10, starting in the first digit with 10 raised to the power of zero.
That should all feel pretty comfortable -- we work with decimal digits every day. The neat thing about number systems is that there is nothing that forces you to have 10 different values in a digit. Our base-10 number system likely grew up because we have 10 fingers, but if we happened to evolve to have eight fingers instead, we would probably have a base-8 number system. You can have base-anything number systems. In fact, there are lots of good reasons to use different bases in different situations.
Computers happen to operate using the base-2 number system, also known as the binary number system (just like the base-10 number system is known as the decimal number system). Find out why and how that works in the next section.
Thursday, January 24, 2008
What's the difference between "Dual Core Technology" and "Intel Core 2 Duo"?
This much answer:
- Dual Core is a technology where two processor cores are fabricated on a single die so as to increase real-time processing performance.while Intel Pentium D andIntel Core2 Duo are Intel Processor Product that use this technology.
- "Dual core technology" was to tell that the Pentium D was a dual core chip. The Core 2 Duo also has dual core technology, however the Core 2 Duo is much better than the Pentium D.
- The Pentium D with dual core technology was Intel's first dual core processor, based on the Pentium 4, and was released in 2005 to get Intel back into competition with AMD, which at the time had the best performing dual core technology with the Athlon 64 X2. After that, Intel quickly released the Core Duo architecture, followed by the Core 2 Duo, both of which were significant updates of the Pentium M architecture used in laptops, and adopted by Intel as the basis of its "Core" platform for desktops and notebooks.
Printer maintenance
Every printer needs an occasional tune-up, particularly if it has not been used for a long time. When lines or poor colors appears in prints, it's time to do a nozzle check. The maintenance process consumes ink, so don't use it unless necessary.Maintenance tools are accessed through the printer driver. Once the procedure begins, let it run full cycle before shutting the printer off.
Nozzle check
When printouts become faint or certain colors fail to print, test whether the print heads are working properly. Use the utility that performs a nozzle check pattern. If the printout shows gaps, clean the nozzles.Cleaning print heads
If the nozzle check indicates that a cleaning is need, or if the printer is completely clogged, clean the print heads. The process removes blockages in the nozzles. Run additional nozzle checks since sometimes cleaning must be performed more than once to be successful. Some printers have a deep cleaning option.
If the nozzle check indicates that a cleaning is need, or if the printer is completely clogged, clean the print heads. The process removes blockages in the nozzles. Run additional nozzle checks since sometimes cleaning must be performed more than once to be successful. Some printers have a deep cleaning option.
Print head alignment
If lines and colors look out of kilter, or there is banding, align the print heads. The process aligns the heads correctly.
If cleaning and alignment do not solve a problem, contact the manufacturer for the cost of repair. If your printer is no longer covered under warranty, assess whether repair costs are worth it. Sometimes buying a new printer, particularly those that come with a full set of ink cartridges, is the best option.
Tuesday, January 1, 2008
If memory serves - computer memory - includes related article
Entrepreneur, April, 1997 by Cheryl J. Goldberg
Is it time to upgrade your computer's memory?
Just a few years ago, the conventional wisdom said that upgrading your existing PC system often made sense. You could easily add a few years of life to your system by upgrading your hard disk, CPU, memory or graphics adaptor. But with today's exceedingly fast-paced changes in computer technology and free-falling prices, that no longer holds true.
"You can get a system for $1,800 this year that cost $4,000 a year ago," says Jim McGregor, senior analyst for In-Stat, a market research and consulting company in Scottsdale, Arizona. "So now I'd say, 'Get as much system as you can, use it as long as you can, and then move on to a new system." McGregor cites just two exceptions to that rule: adding memory or a faster modem. Modems were spotlighted in last month's "Business Bytes"; this month, we focus on what adding memory, or RAM, can do. RAM temporarily stores programs, data and processed information in memory cells as it moves to and from the processor, video card and other peripherals. If you don't have enough high-speed RAM, your computer will temporarily store your data or applications in virtual memory - meaning it uses your hard drive.
Because hard drives use mechanical (rather than electronic) methods to store and retrieve information, using virtual memory significantly slows down your system. Conversely, adding RAM can vastly improve application speed. The good news for potential buyers is that memory prices have been plummeting over the past year - you can currently get a RAM upgrade for about $6 or $7 per megabyte.
* WHEN TO UPGRADE
Memory is always on every techie's list of top upgrades. But that doesn't mean you should automatically add memory to a slow machine. "If your system is less than a 486, sell it," advises McGregor. "It's technologically incompatible with Windows 95." Similarly, if you have a brand-new machine, you probably won't need to upgrade memory, either.
Most computer manufacturers have begun loading new machines with 24MB or 32MB RAM, which is more than adequate for most requirements. It's certainly more than today's applications can use, and it will probably take a year or two before typical applications start requiring that much memory. Even then, probably only the traditionally memory-hungry applications such as games, multimedia or videoconferencing will require additional memory.
Where you may start needing more memory is if you habitually use several applications at one time in different windows. For the most part, memory is a good upgrade. If you have an older Pentium model, or if you have a 486 with 4MB to 8MB RAM, you can probably get another year out of it.
* DO IT YOURSELF?
Determining which type of RAM you need, however, isn't easy. With so many types, in many speeds, sizes and capacities, it's easy to buy the wrong kind. The type of RAM you'll be upgrading is called DRAM (Dynamic RAM). If you own a brand-name PC, upgrades will be relatively straightforward. Call a reputable memory vendor, and tell them your PC's brand and model. The company should be able to find RAM modules that fit your system. But if you have a no-name clone or want to buy your memory at a computer superstore, you'd better know what you're doing. Here are the factors you need to consider:
* SIMMs and DIMMs: First, you need to know whether your computer uses SIMMs (single in-line memory modules) or DIMMs (dual in-line memory modules). A SIMM or DIMM is a plug-in board with a number of RAM chips that fits into a socket on the motherboard. SIMMs come in 30- or 72-pin varieties, while the newer DIMM design has 168 pins. If you have a 486 PC, you're probably using SIMMs with either 30 or 72 pins. Pentium PCs usually use 72-pin SIMMs or 168-pin DIMMs.
* Pins: These are tiny vertical gold bars at the bottom of the memory module. The easiest way to find out how many you have is to remove the PC's cover and measure the size of the module. A 30-pin SIMM is just over 3 inches long, a 72-pin SIMM measures a bit over 4 inches long, and DIMMs are about 5 inches long.
* Memory speed: Most of today's PCs use either 60- or 70-nanosecond (ns) RAM. To determine which speed your computer uses, consult your PC's manual or technical specifications, or ask your vendor. If your PC requires 70ns RAM, you can use the faster 60ns chips, although you won't get any speed advantage. Don't buy RAM that's slower than required because it won't work in your system.
* Memory banks: When you add RAM modules to your PC, you'll need to fill an entire memory bank. On some PCs, one bank can hold four SIMM slots; on others, two SIMMs or one DIMM fill up a bank. If you can't tell by looking at the motherboard, check its documentation to determine what constitutes one memory bank in your PC. If your memory banks are full, you'll need to replace your existing RAM with higher-capacity SIMMs or DIMMs.
Remember, you can't mix memory of different capacities, such as 1MB and 4MB SIMMs, in the same bank. You can, however, mix them in terms of having, say, one bank full of 1MB SIMMs and another bank full of 4MB SIMMs.
* THE FUTURE OF MEMORY
One of the major problems with all RAM used in today's systems is that it can't keep up with processor speeds. For example, you may have a CPU that can run at 200 MHz but memory that runs at only 100 MHz. That causes bottlenecks in your system, and you won't get the performance gains you'd expect from upgrading to a faster CPU.
To solve this problem, vendors are working on new ways to speed up DRAM technology. Again, you need to know what your system supports; you won't get any additional performance gains from high-speed RAM if your system can't support that particular type of RAM. Following is an overview of some of the best RAM technologies out there - and what's coming up next.
* Fast Page Mode (FPM) DRAM was the type of RAM used in older Pentium systems. It's an improvement over older forms of DRAM because it accesses data in the same row faster. If data needed is in the same row as the previous data, the memory controller doesn't have to repeat the row location; it only needs to indicate the next column location. Typical FPM DRAM speeds are close to 30 MHz.
* Extended Data Output (EDO) DRAM reduces the amount of time it takes to read data from memory by transferring data on both the uptick and the downtick of the clock cycle rather than on just one-half of the cycle. It runs at about 50 MHz. This type of fast memory has been added to most Pentium and Pentium Pro systems sold in the past 12 months.
* Burst EDO (BEDO) DRAM is an innovation that allows a "burst," or series of data, to be transmitted from memory with a single request. It runs at about 66 MHz.
* Synchronous RAM (SRAM) synchronizes memory speed with the speed of the internal processor. With current technology, SRAM runs at 100 MHz. While SRAM is starting to appear in some systems, production is not yet high enough to meet demand. As chip production increases, however, SRAM is likely to become the dominant RAM technology over the next six months to a year.
* RDRAM or RAMBUS DRAM is a DRAM chip from Rambus Inc., a memory chip manufacturer. RDRAM will probably become the new standard in the next two years because it has the support of Intel Corp., the largest CPU manufacturer for PC systems. When this type of RAM becomes widely used, it should support high-speed transfer rates of 1.3GB, which will keep up with PC clock speeds. Currently, RDRAM is used only in some game machines and PC graphics applications. If anything can improve your system's speed and life span, it's RAM. With these basics, you should know enough to upgrade your system.
RELATED ARTICLE: In A Flash
Another type of memory you may see mentioned in the trade press these days is flash memory. Flash memory is a hybrid technology that works somewhat like RAM and somewhat like a hard disk. It stores data in memory cells like RAM; but unlike RAM, the data stays in memory after the power is turned off. Because flash memory has a limited life span and storage space, and must be erased in blocks of data rather than single bytes like RAM, it will never replace RAM. But compared with hard drives, flash memory has several advantages. It has no moving parts, so it has a higher tolerance for shock, vibration, extreme temperatures and harsh environments. Flash memory cards are also smaller and faster than hard drives. Thanks to these characteristics, flash memory cards are being used as portable hard drives in rugged situations. They're also used in digital cameras, cellular phones, audio recorders and scanners to store images and voice data; in networking devices to store microcodes and instructions for transferring data; and in printers and print servers to hold fonts or frequently used graphics.
Cheryl J. Goldberg is a former editor of PC Magazine and has reported on the computer industry for more than 14 years. Write to her in care of Entrepreneur, 2392 Morse Ave., Irvine, CA 92614. You can also reach her via CompuServe at 70641,3632.
COPYRIGHT 1997 Entrepreneur Media, Inc.COPYRIGHT 2004 Gale Group
View more issues: Feb 1997, March 1997, May 1997
Bibliography for "If memory serves - computer memory - includes related article"
Cheryl J. Goldberg "If memory serves - computer memory - includes related article". Entrepreneur. April 1997. FindArticles.com. 01 Jan. 2008. http://findarticles.com/p/articles/mi_m0DTI/is_n4_v25/ai_19325215
Is it time to upgrade your computer's memory?
Just a few years ago, the conventional wisdom said that upgrading your existing PC system often made sense. You could easily add a few years of life to your system by upgrading your hard disk, CPU, memory or graphics adaptor. But with today's exceedingly fast-paced changes in computer technology and free-falling prices, that no longer holds true.
"You can get a system for $1,800 this year that cost $4,000 a year ago," says Jim McGregor, senior analyst for In-Stat, a market research and consulting company in Scottsdale, Arizona. "So now I'd say, 'Get as much system as you can, use it as long as you can, and then move on to a new system." McGregor cites just two exceptions to that rule: adding memory or a faster modem. Modems were spotlighted in last month's "Business Bytes"; this month, we focus on what adding memory, or RAM, can do. RAM temporarily stores programs, data and processed information in memory cells as it moves to and from the processor, video card and other peripherals. If you don't have enough high-speed RAM, your computer will temporarily store your data or applications in virtual memory - meaning it uses your hard drive.
Because hard drives use mechanical (rather than electronic) methods to store and retrieve information, using virtual memory significantly slows down your system. Conversely, adding RAM can vastly improve application speed. The good news for potential buyers is that memory prices have been plummeting over the past year - you can currently get a RAM upgrade for about $6 or $7 per megabyte.
* WHEN TO UPGRADE
Memory is always on every techie's list of top upgrades. But that doesn't mean you should automatically add memory to a slow machine. "If your system is less than a 486, sell it," advises McGregor. "It's technologically incompatible with Windows 95." Similarly, if you have a brand-new machine, you probably won't need to upgrade memory, either.
Most computer manufacturers have begun loading new machines with 24MB or 32MB RAM, which is more than adequate for most requirements. It's certainly more than today's applications can use, and it will probably take a year or two before typical applications start requiring that much memory. Even then, probably only the traditionally memory-hungry applications such as games, multimedia or videoconferencing will require additional memory.
Where you may start needing more memory is if you habitually use several applications at one time in different windows. For the most part, memory is a good upgrade. If you have an older Pentium model, or if you have a 486 with 4MB to 8MB RAM, you can probably get another year out of it.
* DO IT YOURSELF?
Determining which type of RAM you need, however, isn't easy. With so many types, in many speeds, sizes and capacities, it's easy to buy the wrong kind. The type of RAM you'll be upgrading is called DRAM (Dynamic RAM). If you own a brand-name PC, upgrades will be relatively straightforward. Call a reputable memory vendor, and tell them your PC's brand and model. The company should be able to find RAM modules that fit your system. But if you have a no-name clone or want to buy your memory at a computer superstore, you'd better know what you're doing. Here are the factors you need to consider:
* SIMMs and DIMMs: First, you need to know whether your computer uses SIMMs (single in-line memory modules) or DIMMs (dual in-line memory modules). A SIMM or DIMM is a plug-in board with a number of RAM chips that fits into a socket on the motherboard. SIMMs come in 30- or 72-pin varieties, while the newer DIMM design has 168 pins. If you have a 486 PC, you're probably using SIMMs with either 30 or 72 pins. Pentium PCs usually use 72-pin SIMMs or 168-pin DIMMs.
* Pins: These are tiny vertical gold bars at the bottom of the memory module. The easiest way to find out how many you have is to remove the PC's cover and measure the size of the module. A 30-pin SIMM is just over 3 inches long, a 72-pin SIMM measures a bit over 4 inches long, and DIMMs are about 5 inches long.
* Memory speed: Most of today's PCs use either 60- or 70-nanosecond (ns) RAM. To determine which speed your computer uses, consult your PC's manual or technical specifications, or ask your vendor. If your PC requires 70ns RAM, you can use the faster 60ns chips, although you won't get any speed advantage. Don't buy RAM that's slower than required because it won't work in your system.
* Memory banks: When you add RAM modules to your PC, you'll need to fill an entire memory bank. On some PCs, one bank can hold four SIMM slots; on others, two SIMMs or one DIMM fill up a bank. If you can't tell by looking at the motherboard, check its documentation to determine what constitutes one memory bank in your PC. If your memory banks are full, you'll need to replace your existing RAM with higher-capacity SIMMs or DIMMs.
Remember, you can't mix memory of different capacities, such as 1MB and 4MB SIMMs, in the same bank. You can, however, mix them in terms of having, say, one bank full of 1MB SIMMs and another bank full of 4MB SIMMs.
* THE FUTURE OF MEMORY
One of the major problems with all RAM used in today's systems is that it can't keep up with processor speeds. For example, you may have a CPU that can run at 200 MHz but memory that runs at only 100 MHz. That causes bottlenecks in your system, and you won't get the performance gains you'd expect from upgrading to a faster CPU.
To solve this problem, vendors are working on new ways to speed up DRAM technology. Again, you need to know what your system supports; you won't get any additional performance gains from high-speed RAM if your system can't support that particular type of RAM. Following is an overview of some of the best RAM technologies out there - and what's coming up next.
* Fast Page Mode (FPM) DRAM was the type of RAM used in older Pentium systems. It's an improvement over older forms of DRAM because it accesses data in the same row faster. If data needed is in the same row as the previous data, the memory controller doesn't have to repeat the row location; it only needs to indicate the next column location. Typical FPM DRAM speeds are close to 30 MHz.
* Extended Data Output (EDO) DRAM reduces the amount of time it takes to read data from memory by transferring data on both the uptick and the downtick of the clock cycle rather than on just one-half of the cycle. It runs at about 50 MHz. This type of fast memory has been added to most Pentium and Pentium Pro systems sold in the past 12 months.
* Burst EDO (BEDO) DRAM is an innovation that allows a "burst," or series of data, to be transmitted from memory with a single request. It runs at about 66 MHz.
* Synchronous RAM (SRAM) synchronizes memory speed with the speed of the internal processor. With current technology, SRAM runs at 100 MHz. While SRAM is starting to appear in some systems, production is not yet high enough to meet demand. As chip production increases, however, SRAM is likely to become the dominant RAM technology over the next six months to a year.
* RDRAM or RAMBUS DRAM is a DRAM chip from Rambus Inc., a memory chip manufacturer. RDRAM will probably become the new standard in the next two years because it has the support of Intel Corp., the largest CPU manufacturer for PC systems. When this type of RAM becomes widely used, it should support high-speed transfer rates of 1.3GB, which will keep up with PC clock speeds. Currently, RDRAM is used only in some game machines and PC graphics applications. If anything can improve your system's speed and life span, it's RAM. With these basics, you should know enough to upgrade your system.
RELATED ARTICLE: In A Flash
Another type of memory you may see mentioned in the trade press these days is flash memory. Flash memory is a hybrid technology that works somewhat like RAM and somewhat like a hard disk. It stores data in memory cells like RAM; but unlike RAM, the data stays in memory after the power is turned off. Because flash memory has a limited life span and storage space, and must be erased in blocks of data rather than single bytes like RAM, it will never replace RAM. But compared with hard drives, flash memory has several advantages. It has no moving parts, so it has a higher tolerance for shock, vibration, extreme temperatures and harsh environments. Flash memory cards are also smaller and faster than hard drives. Thanks to these characteristics, flash memory cards are being used as portable hard drives in rugged situations. They're also used in digital cameras, cellular phones, audio recorders and scanners to store images and voice data; in networking devices to store microcodes and instructions for transferring data; and in printers and print servers to hold fonts or frequently used graphics.
Cheryl J. Goldberg is a former editor of PC Magazine and has reported on the computer industry for more than 14 years. Write to her in care of Entrepreneur, 2392 Morse Ave., Irvine, CA 92614. You can also reach her via CompuServe at 70641,3632.
COPYRIGHT 1997 Entrepreneur Media, Inc.COPYRIGHT 2004 Gale Group
View more issues: Feb 1997, March 1997, May 1997
Bibliography for "If memory serves - computer memory - includes related article"
Cheryl J. Goldberg "If memory serves - computer memory - includes related article". Entrepreneur. April 1997. FindArticles.com. 01 Jan. 2008. http://findarticles.com/p/articles/mi_m0DTI/is_n4_v25/ai_19325215
Subscribe to:
Posts (Atom)