MEMORY CARD

MEMORY CARD

A memory card or flash memory card is solid-state electronic flash memory data storage device capable of storing digital contents. These are mainly used with digital cameras, handheld and Mobile computers, mobile phones, music players, digital cinematography cameras, video game consoles, and other electronics. They offer high re-record-ability, power-free storage, small form factor, and rugged environmental specifications. There are also non-solid-state memory cards that do not use flash memory.

What types of devices need memory cards?

Memory cards first took off as the storage medium of choice in photography, with digital cameras dispensing with film rolls to instead rely on the much smaller and cost effective memory cards. An increasing number of digital video cameras are also becoming memory card compatible.
As well as digital cameras, memory cards are commonly used with many personal digital assistants (PDAs) as a medium for storing data. And as mobile phones become much more feature packed, memory cards are becoming the favoured method of storing information like photos, music and messages.
Memory cards are also making more frequent appearances in other consumer electronic devices such as televisions, portable game devices, printers, DVD recorders and more. Many new televisions now come with card slots which allow users to see any stored photos on a big screen, while some printers allow you to print directly from images stored on a card.
While you can easily swap cards from one product to another, it's important to remember that different devices take different types of memory cards. If you already have a device that takes a memory card and want to buy more gear, make sure your intended purchase can take the same type of card.

1.CompactFlash
CompactFlash remains one of the most popular types of memory cards, and was the first to be designed specifically for digital photography. Its high storage capacity (up to 8GB) means it’s popular with high end digital SLRs, but its large size means you won’t see it inside mobile phones or PDAs. CompactFlash cards are hardy — the cards have an operating shock rating of 2000Gs, which is equivalent to a 3.3m drop.
A possible point of confusion for consumers is that there are two variations of CompactFlash — Type I and Type II. Type II cards are slightly thicker than type I cards and generally have larger storage capacity. While you can use a Type I card in a device that has a Type II slot, Type IIs are usually too thick to fit into a Type I slot.
Size:-36.4 x 42.8 x 3.3mm for Type I
:-36.4 x 42.8 x 5mm for Type II
Capacity:-Available from 32MB to 12GB
Typically found in:-Digital cameras, laptops, PDAs, camcorders, photo printers,MP3 players

2.Memory Stick
A proprietary format developed by Sony, Memory Sticks can be usually found in Sony’s range of consumer electronic devices. The original Memory Sticks topped out at 128MB, but a few years ago Sony released a revision called Memory Stick PRO. Memory Stick PRO delivered faster speeds and greater capacity. Between the original Memory Stick and PRO versions, however, Sony released an interim solution called Memory Stick Select. Select at the time doubled the maximum capacity of a Memory Stick to 256MB.
While you can use older Memory Sticks in new devices, only products that are PRO compliant will be able to use Memory Stick PRO units. Memory Stick PRO cards also feature MagicGate, a content.

Size:-21.45 x 50 x 2.8mm
Capacity:-Available from 64MB to 8GB
Typically found in:-Sony/Sony Ericsson products such as mobile phones, PDAs, televisions and more

3.Memory Stick Duo
Duos are smaller versions of Sony’s Memory Sticks, and have found a niche in some of Sony’s smaller electronic products, such as the PlayStation Portable. Duos have all of the features of the larger Memory Stick, and also come in PRO versions. Duos need an adapter to fit into normal Memory Stick enabled devices.

Size:-20 x 31 x 1.6mm
Capacity:-Available from 256MB to 2GB
Typically found in:-Sony/Sony Ericsson products such as mobile phones, PDAs, Game devices and more.

4.Memory Stick Micro
Memory Stick Micro is Sony’s answer to the microSD (TransFlash) card. With decreasing size yet increasing functionality of mobile phones, space has become a premium in the new generation of Sony Ericsson handsets. The Memory Stick Micro offers the advantages of external add-on capacity without compromising electronics real estate.

Size:-15 x 12.5 x 1.2mm
Capacity:-Available from256MB to 2GB
Typically found in:-Sony Ericsson mobile phones

5.MultiMediaCard (MMC)

Similar in size to SD cards, MMC is another format found mainly in cameras and PDAs.
MMC cards can also be used in SD card devices, but come at generally lower capacities than their more popular cousin.

Size:-24 x 32 x 1.4mm

Capacity:-Available from 32MB to 1GB

Typically found in:-PDAs, mobile phones, camcorders, MP3 players, laptops, digital cameras.

6.Reduced Size MMC (RS-MMC)

Reduced size MMC offer all of the features of standard sized MMC cards but are only half the length.
RS-MMC units usually ship with an adaptor which allows you to use the cards in MMC devices.

Size:-18 x 24 x 1.4mm

Capacity:-Available from 128MB to 1GB

Typically found in:-Mobile phones with multimedia requirements

7.Secure Digital (SD) / Secure Digital High Capacity (SDHC)

The postage stamp size Secure Digital (SD) card is the most popular type of memory card on the market. Its small size, large capacity and robust design has made it common in everything from cameras to MP3 players. Other advantages include relatively high speed data transfer, a mechanical write protect switch to protect data and built-in copyright protection technology.

Size:-32 x 24 x 2.1mm

Capacity:-Available from 32MB to 2GB (SD), 4GB to 32GB (SDHC)

Typically found in:-Digital cameras, PDAs, mobile phones, camcorders, MP3 players, televisions, DVD recorders.

8.miniSD

miniSD cards use the same technology as SD cards, meaning users get all of the advantages of an SD but in a smaller package. These smaller SD cards are used in smaller devices such as mobile phones and MP3 players. minds cards are usually sold with an adaptor which allows you to use the card in a normal SD slot.

Size:-21 x 20 x 1.4mm
Capacity:-Available from 32MB to 2GB
Typically found in:-Mobile phones that offer storage-intensive multimedia features

9.MicroSD (TransFlash)

An even smaller SD variant, the microSD format is currently most popular with mobile phone manufacturers due to its extremely small size. They're almost too small to comfortably hold and swap in and out of devices - be careful when you're handling these little units.

Size:-Approximately 15 x 115 x 1mm

Capacity:-Available from 16MB to 2GB

Typically found in:-Mobile phones that offer storage-intensive multimedia features.

10.SmartMedia

SmartMedia was once the dominant card format when it came to digital photography, but it has been superseded in the past few years by more recent formats like SD. Part of fall could be attributed to its low capacity -- SmartMedia peaked at 128MB in its heyday. While new devices mainly support other card formats, manufacturers are still making SmartMedia cards for use in older equipment.

Size:-45 x 37 x 0.7mm

Capacity:-Available from 64MB to 128MB

Typically found in:-Older model digital cameras and PDAs

11.xD-Picture Card

The xD-Picture Card is yet another proprietary memory card format, this time developed by Olympus and Fujifilm for use in their digital photography products. xD-Picture Cards have been designed to minimise power consumption and therefore save battery life.

Size:-20 x 25 x 1.78mm
Capacity:-Available from 32MB to 2GB
Typically found in:-Digital cameras from Fujifilm and Olympus

Data table of selected memory card formats

Advantages:
Very easily allows you to transport documents from one computer to another.
Small, therefore easy to carry around with you.
They are very useful when doing school work or running businesses - any work done at home can be used at work/ school as well.
It holds a lot more data than a floppy disk.
It is a USB drive so it can be used on any computer system.
Disadvantages:
If you want a memory stick that hold a very big amount of data (like if you are going to use it for a lot of large document) they can be quite expensive to buy.

SATA

The serial ATA (serial advanced technology attachment), or SATA computer bus, is a storage-interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives. The SATA host adapter is integrated into almost all modern consumer laptop computers and desktop motherboards.
Serial ATA was designed to replace the older ATA (AT Attachment) standard (also known as EIDE). It is able to use the same low level commands, but serial ATA host-adapters and devices communicate via a high-speed serial cable over two pairs of conductors. In contrast, the parallel ATA (the redesignation for the legacy ATA specifications) used 16 data conductors each operating at a much lower speed.
SATA offers several compelling advantages over the older parallel ATA (PATA) interface: reduced cable-bulk and cost (reduced from eighty wires to seven), faster and more efficient data transfer, and hot swapping.
Features
Hotplug
All SATA devices support hotplugging. However, proper hotplug support requires the device be running in its native command mode not via IDE emulation, which requires AHCI (Advanced Host Controller Interface). Some of the earliest SATA host adapters were not capable of this and furthermore some older operating systems, such as Windows XP, do not directly support AHCI.
Advanced Host Controller Interface
As their standard interface, modern SATA controllers use the AHCI (Advanced Host Controller Interface), allowing advanced features of SATA such as hotplug and native command queuing (NCQ). If AHCI is not enabled by the motherboard and chipset, SATA controllers typically operate in "IDE emulation" mode which does not allow features of devices to be accessed if the ATA/IDE standard does not support them.
Windows device drivers that are labeled as SATA are usually running in IDE emulation mode unless they explicitly state that they are AHCI mode or in RAID mode. While the drivers included with Windows XP do not support AHCI, AHCI has been implemented by proprietary device drivers. Windows, Windows 7, FreeBSD, Linux with kernel version 2.6.19 onward as well as Solaris and OpenSolaris have native support for AHCI.

Cables, connectors, and ports
Connectors and cables present the most visible differences between SATA and parallel ATA drives. Unlike PATA, the same connectors are used on 3.5-inch SATA hard disks for desktop and server computers and 2.5-inch disks for portable or small computers; this allows 2.5-inch drives to be used in desktop computers with only a mounting bracket and no wiring adapter. Smaller disks may use the mini-SATA spec, suitable for small-form-factor Serial ATA drives and mini SSDs.
There is a special connector (eSATA) specified for external devices, and an optionally implemented provision for clips to hold internal connectors firmly in place. SATA drives may be plugged into SAS controllers and communicate on the same physical cable as native SAS disks, but SATA controllers cannot handle SAS disks.
There are SATA ports (on motherboards of a PC) that can use SATA data cable with locks or clips, thus, reducing the chance of accidentally unplugging while the PC is turned on. So does the same with SATA power connector and SATA data connector connected to a SATA HDD or SATA optical drive . Also, the

re are right-angled and left-angled connectors only on one end of SATA data cable, which can only be used when connecting to a SATA HDD or SATA optical drive.

Comparisons between SATA and SCSI
SCSI currently offers transfer rates higher than SATA, but it uses a more complex bus, usually resulting in higher manufacturing costs. SCSI buses also allow connection of several drives (using multiple channels, 7 or 15 on each channel), whereas SATA allows one drive per channel, unless using a port multiplier.
SATA 3 Gbit/s offers a maximum bandwidth of 300 MB/s per device compared to SCSI with a maximum of 320 MB/s. Also, SCSI drives provide greater sustained throughput than SATA drives because of disconnect-reconnect and aggregating performance. SATA devices generally link compatibly to SAS enclosures and adapters, while SCSI devices cannot be directly connected to a SATA bus.
SCSI, SAS and fibre-channel (FC) drives are typically more expensive so they are traditionally used in servers and disk arrays where the added cost is justifiable. Inexpensive ATA and SATA drives evolved in the home-computer market hence there is a view that they are less reliable. As those two worlds overlapped, the subject of reliability became somewhat controversial. Note that, generally, the failure rate of a disk drive is related to the quality of its heads, platters and supporting manufacturing processes, not to its interface.

Difference between IDE, SCSI and SATA
Integrated Drive Electronics (IDE) is one of the oldest interfaces for hard drives, marking a new era in computer history. It was the first interface to make hard drives affordable for everyone. The most prominent feature of IDE is that there was little cabling when hooking up a hard drive to the computer, which led to a hassle-free setup. IDE was introduced in 1986 Compaq computers.

Small Computer System Interface (SCSI) is a standard amongst certain devices that can be connected to a computer, such as hard drives. SCSI was introduced in 1986 as a component of Apple and Amiga computers. The basic idea was to give a faster alternative to Integrated Drive Electronics (IDE) and present an interface which almost any device can be designed to communicate with. Hard drives are the most popular devices that support SCSI, since it has a much higher bandwidth capacity than IDE. However, this high bandwidth capacity comes at a price. Most people do not find such hard drives worth the expense. Those who do invest plenty of money in SCSI hard drives are usually data centers and large companies that host their own servers.

The advent of Serial AT Attachment (SATA) in 2003 was successful and quickly became affordable to the public. The specific design of SATA was to beat the IDE benchmarks and render IDE obsolete. Its first release had a 1.5 GB/s throughput, and new versions of it just keep coming. The high bandwidth and affordability makes it perfect for home users and data centers alike. After SATA was introduced, motherboard manufacturers quickly put aside IDE and gave more importance to SATA technology.

IDE->INTEGRATED DRIVE ELECTRONICS

IDE CONTROLLER WORKS

Most personal computers have one or more of the following storage devices:

• Floppy drive
• Hard drive
• CD-ROM drive

Usually, these devices connect to the computer through an Integrated Drive Electronics (IDE) interface. Essentially, an IDE interface is a standard way for a storage device to connect to a computer. IDE is actually not the true technical name for the interface standard. The original name, AT Attachment (ATA), signified that the interface was initially developed for the IBM AT computer. In this article, you will learn about the evolution of IDE/ATA, what the pinouts are and exactly what "slave" and "master" mean in IDE.

The Integrated Drive Electronics interface is the most popular way to connect a hard drive to a PC.

Drives that use the interface officially known as AT Attachment or ATA are also often called something else entirely: Integrated Drive Electronics or IDE drives. In fact, the term "IDE" is probably more widely used than the correct name for the interface! (This is changing, however, as new terms such as "Ultra ATA" grow in popularity.) IDE can be considered the unofficial "overall name" for this hard disk interface; it has been used since the earliest days of these drives, and will probably always be used by a large segment of the industry.

The reason for the name, of course, is that the IDE interface was the first where the logic board was integrated on the hard disk itself. As described in some detail in the overview and history of the interface, drives prior to this point had the hard drive control logic on a separate controller card that plugged in a system bus slot. This led to a number of compatibility and reliability problems that were corrected by mating the logic board to the hard disk itself.

The name "IDE" really reflects this design decision and has nothing to do with the interface per se. Today, all drives have integrated logic boards, including those that use interfaces quite different from ATA, such as SCSI or USB. However, habits are hard to break in the computer world, and use of the name persists. This has the potential for confusion, though most people today know that "IDE" refers to the IDE/ATA interface specifically. (One of the reasons that the name "IDE" was never adopted for the formal standards is that the developers of the standards considered it confusing.)

It's important to remember that today, being told that a particular drive is an "IDE drive" tells you only that it uses some variant of the IDE/ATA interface. "IDE" by itself is a generic term that does not tell you anything about the drive, such as what modes it supports or what official standard it adheres to. You need to find out more about the drive to understand the details of its interface.

IDE Evolution

IDE was created as a way to standardize the use of hard drives in computers. The basic concept behind IDE is that the hard drive and the controller should be combined. The controller is a small circuit board with chips that provide guidance as to exactly how the hard drive stores and accesses data. Most controllers also include some memory that acts as a buffer to enhance hard drive performance.

Before IDE, controllers and hard drives were separate and often proprietary. In other words, a controller from one manufacturer might not work with a hard drive from another manufacturer. The distance between the controller and the hard drive could result in poor signal quality and affect performance. Obviously, this caused much frustration for computer users

The birth of the IDE interface led to combining a controller like this one with a hard drive

While the IDE interface was originally developed for connecting hard drives, it has evolved into the universal interface for connecting internal floppy drives, CD-ROM drives and even some tape backup drives. Although it is very popular for internal drives, IDE is rarely used for attaching an external device.

There are several variations of ATA, each one adding to the previous standard and maintaining backward compatibility.

The standards include:

• ATA-1 - The original specification that Compaq included in the Deskpro 386. It instituted the use of a master/slave configuration. ATA-1 was based on a subset of the standard ISA 96-pin connector that uses either 40 or 44 pin connectors and cables. In the 44-pin version, the extra four pins are used to supply power to a drive that doesn't have a separate power connector. Additionally, ATA-1 provides signal timing for direct memory access (DMA) and programmed input/output (PIO) functions. DMA means that the drive sends information directly to memory, while PIO means that the computer's central processing unit (CPU) manages the information transfer. ATA-1 is more commonly known as IDE.
• ATA-2 - DMA was fully implemented beginning with the ATA-2 version. Standard DMA transfer rates increased from 4.16 megabytes per second (MBps) in ATA-1 to as many as 16.67 MBps. ATA-2 provides power management, PCMCIA card support and removable device support. ATA-2 is often called EIDE (Enhanced IDE), Fast ATA or Fast ATA-2. The total hard drive size supported increased to 137.4 gigabytes. ATA-2 provided standard translation methods for Cylinder Head Sector (CHS) for hard drives up to 8.4 gigabytes in size. CHS is how the system determines where the data is located on a hard drive. The reason for the big discrepancy between total hard drive size and CHS hard drive support is because of the bit sizes used by the basic input/output system (BIOS) for CHS. CHS has a fixed length for each part of the address.
• ATA-3 - With the addition of Self-Monitoring Analysis and Reporting Technology (SMART), IDE drives were made more reliable. ATA-3 also adds password protection to access drives, providing a valuable security feature.

• ATA-4 - Probably the two biggest additions to the standard in this version are Ultra DMA support and the integration of the AT Attachment Program Interface (ATAPI) standard. ATAPI provides a common interface for CD-ROM drives, tape backup drives and other removable storage devices. Before ATA-4, ATAPI was a completely separate standard. With the inclusion of ATAPI, ATA-4 immediately improved the removable media support of ATA. Ultra DMA increased the DMA transfer rate from ATA-2's 16.67 MBps to 33.33 MBps. In addition to the existing cable that uses 40 pins and 40 conductors (wires), this version introduces a cable that has 80 conductors. The other 40 conductors are ground wires interspersed between the standard 40 conductors to improve signal quality. ATA-4 is also known as Ultra DMA, Ultra ATA and Ultra ATA/33.

• ATA-5 - The major update in ATA-5 is auto detection of which cable is used: the 40-conductor or 80-conductor version. Ultra DMA is increased to 66.67 MB/sec with the use of the 80-conductor cable. ATA-5 is also called Ultra ATA/66.

Cable Key

IDE devices use a ribbon cable to connect to each other. Ribbon cables have all of the wires laid flat next to each other instead of bunched or wrapped together in a bundle. IDE ribbon cables have either 40 or 80 wires. There is a connector at each end of the cable and another one about two-thirds of the distance from the motherboard connector. This cable cannot exceed 18 inches (46 cm) in total length (12 inches from first to second connector, and 6 inches from second to third) to maintain signal integrity. The three connectors are typically different colors and attach to specific items:

• The blue connector attaches to the motherboard.
• The black connector attaches to the primary (master) drive.
• The grey connector attaches to the secondary (slave) drive.

Along one side of the cable is a stripe. This stripe tells you that the wire on that side is attached to Pin 1 of each connector. Wire 20 is not connected to anything. In fact, there is no pin at that position. This position is used to ensure that the cable is attached to the drive in the correct position. Another way that manufacturers make sure the cable is not reversed is by using a cable key. The cable key is a small, plastic square on top of the connector on the ribbon cable that fits into a notch on the connector of the device. This allows the cable to attach in only one position.

Masters and Slaves

A single IDE interface can support two devices. Most motherboards come with dual IDE interfaces (primary and secondary) for up to four IDE devices. Because the controller is integrated with the drive, there is no overall controller to decide which device is currently communicating with the computer. This is not a problem as long as each device is on a separate interface, but adding support for a second drive on the same cable took some ingenuity.

To allow for two drives on the same cable, IDE uses a special configuration called master and slave. This configuration allows one drive's controller to tell the other drive when it can transfer data to or from the computer. What happens is the slave drive makes a request to the master drive, which checks to see if it is currently communicating with the computer. If the master drive is idle, it tells the slave drive to go ahead. If the master drive is communicating with the computer, it tells the slave drive to wait and then informs it when it can go ahead.

The computer determines if there is a second (slave) drive attached through the use of Pin 39 on the connector. Pin 39 carries a special signal, called Drive Active/Slave Present (DASP), that checks to see if a slave drive is present.

Although it will work in either position, it is recommended that the master drive is attached to the connector at the very end of the IDE ribbon cable. Then, a jumper on the back of the drive next to the IDE connector must be set in the correct position to identify the drive as the master drive. The slave drive must have either the master jumper removed or a special slave jumper set, depending on the drive. Also, the slave drive is attached to the connector near the middle of the IDE ribbon cable. Each drive's controller board looks at the jumper setting to determine whether it is a slave or a master. This tells them how to perform. Every drive is capable of being either slave or master when you receive it from the manufacturer. If only one drive is installed, it should always be the master drive.

Many drives feature an option called Cable Select (CS). With the correct type of IDE ribbon cable, these drives can be auto configured as master or slave. CS works like this: A jumper on each drive is set to the CS option. The cable itself is just like a normal IDE cable except for one difference -- Pin 28 only connects to the master drive connector. When your computer is powered up, the IDE interface sends a signal along the wire for Pin 28. Only the drive attached to the master connector receives the signal. That drive then configures itself as the master drive. Since the other drive received no signal, it defaults to slave mode.

USB->UNIVERSAL SERIAL BUS

Just about any computer that you buy today comes with one or more Universal Serial Bus connectors on the back. These USB connectors let you attach everything from mice to printers to your computer quickly and easily. The operating system supports USB as well, so the installation of the device drivers is quick and easy, too. Compared to other ways of connecting devices to your computer (including parallel ports, serial ports and special cards that you install inside the computer's case), USB devices are incredibly simple!

In this article, we will look at USB ports from both a user and a technical standpoint. You will learn why the USB system is so flexible and how it is able to support so many devices so easily -- it's truly an amazing system!

Anyone who has been around computers for more than two or three years knows the problem that the Universal Serial Bus is trying to solve -- in the past, connecting devices to computers has been a real headache!

• Printers connected to parallel printer ports, and most computers only came with one. Things like Zip drives, which need a high-speed connection into the computer, would use the parallel port as well, often with limited success and not much speed.
• Modems used the serial port, but so did some printers and a variety of odd things like Palm Pilots and digital cameras. Most computers have at most two serial ports, and they are very slow in most cases.
• Devices that needed faster connections came with their own cards, which had to fit in a card slot inside the computer's case. Unfortunately, the number of card slots is limited and you needed a Ph.D. to install the software for some of the cards.

The goal of USB is to end all of these headaches. The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer.

Just about every peripheral made now comes in a USB version. A sample list of USB devices that you can buy today includes:

• Printers
• Scanners
• Mice
• Joysticks
• Flight yokes
• Digital cameras
• Webcams
• Scientific data acquisition devices
• Modems
• Speakers
• Telephones
• Video phones
• Storage devices such as Zip drives
• Network connections

In the next section, we'll look at the USB cables and connectors that allow your computer to communicate with these devices.

USB Hubs

Most computers that you buy today come with one or two USB sockets. With so many USB devices on the market today, you easily run out of sockets very quickly. For example, on the computer that I am typing on right now, I have a USB printer, a USB scanner, a USB Webcam and a USB network connection. My computer has only one USB connector on it, so the obvious question is, "How do you hook up all the devices?"

The easy solution to the problem is to buy an inexpensive USB hub. The USB standard supports up to 127 devices, and USB hubs are a part of the standard.

USB Cables and Connectors

Connecting a USB device to a computer is simple,we can find the USB connector on the back of your machine and plug the USB connector into it.

The rectangular socket is a typical USB socket on the back of a PC.

If it is a new device, the operating system auto-detects it and asks for the driver disk. If the device has already been installed, the computer activates it and starts talking to it. USB devices can be connected and disconnected at any time.

A typical USB connector, called an "A" connection

A typical USB four-port hub accepts 4 "A" connections.

A hub typically has four new ports, but may have many more. You plug the hub into your computer, and then plug your devices (or other hubs) into the hub. By chaining hubs together, you can build up dozens of available USB ports on a single computer.

Hubs can be powered or unpowered. As you will see on the next page, the USB standard allows for devices to draw their power from their USB connection. Obviously, a high-power device like a printer or scanner will have its own power supply, but low-power devices like mice and digital cameras get their power from the bus in order to simplify them. The power (up to 500 milliamps at 5 volts) comes from the computer. If you have lots of self-powered devices (like printers and scanners), then your hub does not need to be powered -- none of the devices connecting to the hub needs additional power, so the computer can handle it. If you have lots of unpowered devices like mice and cameras, you probably need a powered hub. The hub has its own transformer and it supplies power to the bus so that the devices do not overload the computer's supply.

The USB Process

When the host powers up, it queries all of the devices connected to the bus and assigns each one an address. This process is called enumeration -- devices are also enumerated when they connect to the bus. The host also finds out from each device what type of data transfer it wishes to perform:

• Interrupt - A device like a mouse or a keyboard, which will be sending very little data, would choose the interrupt mode.
• Bulk - A device like a printer, which receives data in one big packet, uses the bulk transfer mode. A block of data is sent to the printer (in 64-byte chunks) and verified to make sure it is correct.
• Isochronous - A streaming device (such as speakers) uses the isochronous mode. Data streams between the device and the host in real-time, and there is no error correction.

The host can also send commands or query parameters with control packets.

As devices are enumerated, the host is keeping track of the total bandwidth that all of the isochronous and interrupt devices are requesting. They can consume up to 90 percent of the 480 Mbps of bandwidth that is available. After 90 percent is used up, the host denies access to any other isochronous or interrupt devices. Control packets and packets for bulk transfers use any bandwidth left over (at least 10 percent).

The Universal Serial Bus divides the available bandwidth into frames, and the host controls the frames. Frames contain 1,500 bytes, and a new frame starts every millisecond. During a frame, isochronous and interrupt devices get a slot so they are guaranteed the bandwidth they need. Bulk and control transfers use whatever space is left. The technical links at the end of the article contain lots of detail if you would like to learn more.

USB Features

The Universal Serial Bus has the following features:

• The computer acts as the host.
• Up to 127 devices can connect to the host, either directly or by way of USB hubs.
• Individual USB cables can run as long as 5 meters; with hubs, devices can be up to 30 meters (six cables' worth) away from the host.
• With USB 2.,the bus has a maximum data rate of 480 megabits per second.
• A USB cable has two wires for power (+5 volts and ground) and a twisted pair of wires to carry the data.
• On the power wires, the computer can supply up to 500 milliamps of power at 5 volts.
• Low-power devices (such as mice) can draw their power directly from the bus. High-power devices (such as printers) have their own power supplies and draw minimal power from the bus. Hubs can have their own power supplies to provide power to devices connected to the hub.
• USB devices are hot-swappable, meaning you can plug them into the bus and unplug them any time.
• Many USB devices can be put to sleep by the host computer when the computer enters a power-saving mode.
• The devices connected to a USB port rely on the USB cable to carry power and data.

Inside a USB cable: There are two wires for power -- +5 volts (red) and ground (brown) -- and a twisted pair (yellow and blue) of wires to carry the data. The cable is also shielded.

USB 2.0

The standard for USB version 2.0 was released in April 2000 and serves as an upgrade for USB 1.1.

USB 2.0 (High-speed USB) provides additional bandwidth for multimedia and storage applications and has a data transmission speed 40 times faster than USB 1.1. To allow a smooth transition for both consumers and manufacturers, USB 2.0 has full forward and backward compatibility with original USB devices and works with cables and connectors made for original USB, too.

Supporting three speed modes (1.5, 12 and 480 megabits per second), USB 2.0 supports low-bandwidth devices such as keyboards and mice, as well as high-bandwidth ones like high-resolution Webcams, scanners, printers and high-capacity storage systems. The deployment of USB 2.0 has allowed PC industry leaders to forge ahead with the development of next-generation PC peripherals to complement existing high-performance PCs. The transmission speed of USB 2.0 also facilitates the development of next-generation PCs and applications. In addition to improving functionality and encouraging innovation, USB 2.0 increases the productivity of user applications and allows the user to run multiple PC applications at once or several high-performance peripherals simultaneously.

OPTICAL DISK DRIVE

What is an Optical Disc Drive?

Optical drives retrieve and/or store data on optical discs like CDs, DVDs, and BDs (Blu-ray discs).Some common types of optical drives include CD-ROM, CD-RW, DVD-ROM, DVD?RW, and Blu-ray drives. CD and DVD writers, such as CD-R and DVD-R drives use a laser to both read and write data on the discs. The laser used for writing the data is much more powerful than the laser that reads the data, as it "burns" the bumps and dips into the disc. While optical drives can spin discs at very high speeds, they are still significantly slower than hard drives, which store data magnetically.

Optical Disc Drive Description:
An optical drive is about the size of a thick soft cover book. The front of the drive has a small Open/Close button that ejects and retracts the drive bay door. This is how media like CDs, DVDs, and BDs are inserted into and removed from the drive.The sides of the optical drive have pre-drilled, threaded holes for easy mounting in the 5.25 inch drive bay in the computer case. The optical drive is mounted so the end with the connections faces inside the computer and the end with the drive bay faces outside.The back end of the optical drive contains a port for a cable that connects to the motherboard. The type of cable used will depend on the type of drive but is almost always included with an optical drive purchase. Also here is a connection for power from the power supply.Most optical drives also have jumper settings on the back end that define how the motherboard is to recognize the drive when more than one is present. These settings vary from drive to drive so check with your optical drive manufacturer for details.

Computer interfaces
Most internal drives for personal computers, servers and workstations are designed to fit in a standard 5.25" drive bay and connect to their host via an ATA or SATA interface. External drives usually have USB or FireWire interfaces. Some portable versions for laptop use power themselves off batteries or off their interface bus.
Drives with SCSI interface exist, but are less common and tend to be more expensive, because of the cost of their interface chipsets and more complex SCSI connectors.When the optical disc drive was first developed, it was not easy to add to computer systems. Some computers such as the IBM PS/2 were standardizing on the 3.5" floppy and 3.5" hard disk, and did not include a place for a large internal device. Also IBM PCs and clones at first only included a single ATA drive interface, which by the time the CDROM was introduced, was already being used to support two hard drives. Early laptops simply had no built-in high-speed interface for supporting an external storage device.
This was solved through several techniques:
Early sound cards could include a second ATA interface, though it was often limited to supporting a single optical drive and no hard drives. This evolved into the modern second ATA interface included as standard equipment
1. A parallel port external drive was developed that connected between a printer and the computer. This was slow but an option for laptops.
2. A PCMCIA optical drive interface was also developed for laptops .
3. A SCSI card could be installed in desktop PCs for an external SCSI drive enclosure, though SCSI was typically much more expensive than other options .

WINDOWS 7

Windows 7 is the latest public release version of Microsoft Windows, a series of operating systems produced by Microsoft for use on personal computers, including home and business desktops, laptops, netbooks, tablet PCs, and media center PCs. Windows 7 was released to manufacturing on July 22, 2009, and reached general retail availability on October 22, 2009, less than three years after the release of its predecessor, Windows Vista. Windows 7's server counterpart, Windows Server 2008 R2, was released at the same time.
Unlike its predecessor, which introduced a large number of new features, Windows 7 was intended to be a more focused, incremental upgrade to the Windows line, with the goal of being fully compatible with applications and hardware with which Windows Vista is already compatible. Presentations given by Microsoft in 2008 focused on multi-touch support, a redesigned Windows Shell with a new taskbar, referred to as the Superbar, a home networking system called HomeGroup, and performance improvements. Some applications that have been included with prior releases of Microsoft Windows, including Windows Calendar, Windows Mail, Windows Movie Maker, and Windows Photo Gallery, are not included in Windows 7; most are instead offered separately as part of the free Windows Live Essentials suite.
Minimum hardware requirements for Windows 7

Removed features(AS compared to windows xp and windows vista)
A number of capabilities and certain programs that were a part of Windows Vista are no longer present or have been changed, resulting in the removal of certain functionality. Some notable Windows Vista features and components have been replaced or removed in Windows 7, including the classic Start Menu user interface, Windows Ultimate Extras and InkBall. Four applications bundled with Windows Vista — Windows Photo Gallery, Windows Movie Maker, Windows Calendar and Windows Mail — are not included with Windows 7, but are instead available for free in a separate package called Windows Live Essentials.

INSTALLATION
Installation Microsoft is offering several paths to install Windows 7. People can buy a new computer with the operating system already installed, upgrade from Windows XP or Vista, or do a clean install on a computer the user already owns. The clean installation took us about 30 minutes, but that will vary depending on your computer.
The upgrade procedure is different depending on whether you're running Windows XP or Windows Vista. Vista users merely need to back up their data before choosing the Upgrade option from the install disc. Both XP Home and XP Pro users will have to back up their data, then choose Custom from the install disc. Custom will have the same effect as a clean install, although it'll save your old data in a folder called Windows.old. Once you choose Custom, you'll need to select the partition of your hard drive that contains Windows XP, and then follow the instructions to enter your product key and allow the computer to reboot as needed.
FEATURES
DESKTOP Themes
Support for themes has been extended in Windows 7. In addition to setting the colors of the window chrome, desktop background, desktop icons, mouse pointers and sound schemes, themes in Windows 7 include desktop slideshow settings. A new control panel interface, accessible through the "Personalize" context menu item on the desktop, has been introduced which provides the ability to customize and switch between themes, as well as download more themes from Microsoft's web site. Support for "theme packs" is included; theme packs are cabinet files with an extension of .themepack, and consist of a .theme as well as any number of image, sound, icon, and mouse cursor files. Windows 7 recognizes this file format and will switch the user's theme to the theme contained inside when opened.

Desktop Slideshow
Windows Explorer includes a desktop slideshow that changes the desktop background in a designated amount of time with a smooth fading transition. This feature supports pre-downloaded sets of wallpapers and also supports photo RSS feed.
Gadgets
Windows Vista introduced Gadgets and a sidebar which provides the ability to anchor Gadgets to the side of the user's desktop. In Windows 7, the sidebar has been removed, while gadgets can still be placed on the desktop. Windows 7 adds a Windows Media Center gadget to the default collection while removing the Contacts and Notes gadgets.
Managing gadgets is more closely integrated with Windows Explorer, but the gadgets themselves continue to operate in a separate sidebar.exe process.The Desktop context menu includes a new "Gadgets" menu option to access the gadget gallery, and a "View" sub-menu option to show or hide gadgets. Hiding gadgets results in the sidebar.exe process being unloaded, which Microsoft says is a power-saving practice. Unlike Windows Vista, all gadgets run in a single process, which saves memory, and the process is not run at all if the user has no gadgets on the desktop.
Branding and customization
OEMs and enterprises are able to customize the logon screen wallpaper of Windows 7 that is displayed before a user logs on.
Libraries
Windows Explorer in Windows 7 supports Libraries, virtual folders described in a .library-ms file that aggregates content from various locations - including shared folders on networked systems if the shared folder has been indexed by the host system - and present them in a unified view. Searching in a library automatically federates the query to the remote systems, in addition to searching on the local system, so that files on the remote systems are also searched. Unlike search folders, Libraries are backed by a physical location which allows files to be saved in the Libraries. Such files are transparently saved in the backing physical folder. The default save location for a library may be configured by the user, as can the default view layout for each library. Libraries are generally stored in the Libraries special folder, which allows them to be displayed on the navigation pane.
Federated search
Windows Explorer also supports federating search to external data sources, such as custom databases or web services, that are exposed over the web and described via an OpenSearch definition. The federated location description (called a Search Connector) is provided as a .osdx file. Once installed, the data source becomes queryable directly from Windows Explorer. Windows Explorer features, such as previews and thumbnails, work with the results of a federated search as well.
Start menu
The start orb now has a fade-in highlight effect when the user moves the mouse over it.
Windows 7's Start menu retains the two-column layout of its predecessors, with several functional changes:
The "Documents", "Pictures" and "Music" buttons now link to the Libraries of the same name.
A "Devices and Printers" option has been added that displays a new device manager.
The "shut down" icon in Windows Vista has been replaced with a text link indicating what action will be taken when the icon is clicked. The default action to take is now configurable through the
Taskbar and Start Menu Properties window.
Taskbar Jump Lists are presented in the Start Menu via a guillemet; when the user moves his or her mouse over the guillemet, or presses the right-arrow key, the right-hand side of the Start menu is widened and replaced with the application's Jump List.
Taskbar
The Windows Taskbar has seen its most significant revision since its introduction in Windows 95. The taskbar is 10 pixels taller than in Windows Vista to accommodate touch screen input and a new larger default icon size, though a smaller taskbar size is available. Running applications are denoted by a border frame around the icon, while applications can be pinned to the taskbar, so that shortcuts to them appear when they are not running. Within this border, a color effect (dependent on the predominant RGB value of the icon) that follows the mouse also indicates the opened status of the application. The glass taskbar is also more transparent. Taskbar buttons show icons by default, not application titles, unless they are set to not combine. Only icons are shown when the application is not running.
Window management mouse gestures
Aero Snap; Window maximizing and tiling
Windows can be dragged to the top of the screen to maximize them and dragged away to restore them. Dragging a window to the left or right of the screen makes it take up half the screen allowing the user to tile two windows next to each other. Also resizing the window to the bottom of the screen or top will extend the window full but retain the width of the window. These features can be disabled via the Ease of Access Center if users do not wish the windows to automatically resize.

Aero Shake

Aero Shake allows users to clear up any clutter on their screen by shaking (dragging back and forth) a window of their choice with the mouse. All other windows will minimize, while the window the user shook stays active on the screen. When the window is shaken again, they are all restored, similar to desktop preview.
Multi-touch
Hilton Locke, who worked on the Tablet PC team at Microsoft, reported on December 11, 2007 that Windows 7 will have new touch features. An overview of the multi-touch capabilities, including a virtual piano program, a mapping and directions program and a touch-aware version of Paint, was demonstrated at the All Things Digital Conference on May 27, 2008. A video demonstrating the multi-touch capabilities was later made available on the web on the same day. Desktop Window Manager
First introduced in Windows Vista, the Desktop Window Manager (DWM) in Windows 7 has been updated to use version 10.1 of Direct3D API, and its performance has been improved significantly.The Desktop Window Manager still requires at least a Direct3D 9-capable video card (supported with new D3D10_FEATURE_LEVEL_9_n device type introduced with the Direct3D 11 runtime).With a video driver conforming to Windows Display Driver Model v1.1, DXGI kernel in Windows 7 provides 2D hardware acceleration to APIs such as GDI, Direct2D and DirectWrite (though GDI+ was not updated to use this functionality). This allows DWM to use significantly lower amounts of system memory, which do not grow regardless of how many windows are opened, like it was in Windows Vista. Systems equipped with a WDDM 1.0 video card will operate in the same fashion as in Windows Vista, using software-only rendering.The Desktop Window Manager in Windows 7 also adds support for systems using multiple heterogeneous graphics cards from different vendors
Font management
The user interface for font management has been overhauled. As with Windows Vista, the collection of installed fonts is shown in a Windows Explorer window, but fonts from the same font family appear as "stacks" instead of as individual icons. A user can then double-click on the font stack and see the individual font. A preview of the font is displayed as part of the icon as well. New options for hiding installed fonts are included; a hidden font remains installed, but is not enumerated when an application asks for a list of available fonts. Windows Vista had received considerable criticism for including the same "Add Font" dialog that had existed as far back as Windows NT 3.1; this dialog has been removed.
The Font dialog box has also been updated to show previews of the font selection in the selection lists. The fontview.exe default font viewing application has replaced the "Properties" button with a "Install" button.
Security / networking
Microsoft had already done a lot of work since the initial release of Vista on not bugging us incessantly with pop-up security nags, but Windows 7 strikes an even better balance. What is disconcerting is how often security warnings include an "unknown" as the publisher -- it's not really teaching anybody to be judicious about what pops up in the warning if the warning itself doesn't even know what's going on. In the end we'll find out just how secure Windows 7 is once it's in the wild and hackers start hammering on it, but with the abundance and ease of Windows updates these days, most anybody with an ounce of common sense and a speedy internet connection should be able to steer clear of danger. Meaning: we're all doomed.

HOW TO MAKE INTEL PROCESSOR

STEP BY STEP PROCESS FOR MAKING A PROCESSOR

Sand:- Made up of 25 percent silicon, is, after oxygen, the second most abundant chemical element that's in the earth's crust. Sand, especially quartz, has high percentages of silicon in the form of silicon dioxide (SiO2) and is the base ingredient for semiconductor manufacturing.

After procuring raw sand and separating the silicon, the excess material is disposed of and the silicon is purified in multiple steps to finally reach semiconductor manufacturing quality which is called electronic grade silicon. The resulting purity is so great that electronic grade silicon may only have one alien atom for every one billion silicon atoms. After the purification process, the silicon enters the melting phase. In this picture you can see how one big crystal is grown from the purified silicon melt. The resulting mono-crystal is called an ingot.

A mono-crystal ingot is produced from electronic grade silicon. One ingot weighs approximately 100 kilograms (or 220 pounds) and has a silicon purity of 99.9999 percent.

The ingot is then moved onto the slicing phase where individual silicon discs, called wafers, are sliced thin. Some ingots can stand higher than five feet. Several different diameters of ingots exist depending on the required wafer size. Today, CPUs are commonly made on 300 mm wafers.

Once cut, the wafers are polished until they have flawless, mirror-smooth surfaces. Intel doesn't produce its own ingots and wafers, and instead purchases manufacturing-ready wafers from third-party companies. Intel’s advanced 45 nm High-K/Metal Gate process uses wafers with a diameter of 300 mm (or 12-inches). When Intel first began making chips, it printed circuits on 50 mm (2-inches) wafers. These days, Intel uses 300 mm wafers, resulting in decreased costs per chip.

The blue liquid, depicted above, is a photo resist finish similar to those used in film for photography. The wafer spins during this step to allow an evenly-distributed coating that's smooth and also very thin.

At this stage, the photo-resistant finish is exposed to ultra violet (UV) light. The chemical reaction triggered by the UV light is similar to what happens to film material in a camera the moment you press the shutter button.Areas of the resist on the wafer that have been exposed to UV light will become soluble. The exposure is done using masks that act like stencils. When used with UV light, masks create the various circuit patterns. The building of a CPU essentially repeats this process over and over until multiple layers are stacked on top of each other.A lens (middle) reduces the mask's image to a small focal point. The resulting "print" on the wafer is typically four times smaller, linearly, than the mask's pattern.

In the picture we have a representation of what a single transistor would appear like if we could see it with the naked eye. A transistor acts as a switch, controlling the flow of electrical current in a computer chip. Intel researchers have developed transistors so small that they claim roughly 30 million of them could fit on the head of a pin.

After being exposed to UV light, the exposed blue photo resist areas are completely dissolved by a solvent. This reveals a pattern of photo resist made by the mask. The beginnings of transistors, interconnects, and other electrical contacts begin to grow from this point.

The photo resist layer protects wafer material that should not be etched away. Areas that were exposed will be etched away with chemicals.

After the etching, the photo resist is removed and the desired shape becomes visible.

More photo resist (blue) is applied and then re-exposed to UV light. Exposed photo resist is then washed off again before the next step, which is called ion doping. This is the step where ion particles are exposed to the wafer, allowing the silicon to change its chemical properties in a way that allows the CPU to control the flow of electricity.

Through a process called ion implantation (one form of a process called doping) the exposed areas of the silicon wafer are bombarded with ions. Ions are implanted in the silicon wafer to alter the way silicon in these areas conduct electricity. Ions are propelled onto the surface of the wafer at very high velocities. An electrical field accelerates the ions to a speed of over 300,000 km/hour (roughly 185,000 mph)

After the ion implantation, the photo resist will be removed and the material that should have been doped (green) now has alien atoms implanted.

This transistor is close to being finished. Three holes have been etched into the insulation layer (magenta color) above the transistor. These three holes will be filled with copper, which will make up the connections to other transistors.

The wafers are put into a copper sulphate solution at this stage. Copper ions are deposited onto the transistor through a process called electroplating. The copper ions travel from the positive terminal (anode) to the negative terminal (cathode) which is represented by the wafer.

The copper ions settle as a thin layer on the wafer surface.

The excess material is polished off leaving a very thin layer of copper.

Multiple metal layers are created to interconnects (think wires) in between the various transistors. How these connections have to be “wired” is determined by the architecture and design teams that develop the functionality of the respective processor (for example, Intel’s Core i7 processor). While computer chips look extremely flat, they may actually have over 20 layers to form complex circuitry. If you look at a magnified view of a chip, you will see an intricate network of circuit lines and transistors that look like a futuristic, multi-layered highway system.

This fraction of a ready wafer is being put through a first functionality test. In this stage test patterns are fed into every single chip and the response from the chip monitored and compared to "the right answer."

After tests determine that the wafer has a good yield of functioning processor units, the wafer is cut into pieces (called dies).

The dies that responded with the right answer to the test pattern will be put forward for the next step (packaging). Bad dies are discarded. Several years ago, Intel made key chains out of bad CPU dies.

This is an individual die, which has been cut out in the previous step (slicing). The die shown here is a die of an Intel Core i7 processor.

The substrate, the die, and the heatspreader are put together to form a completed processor. The green substrate builds the electrical and mechanical interface for the processor to interact with the rest of the PC system. The silver heatspreader is a thermal interface where a cooling solution will be applied. This will keep the processor cool during operation.

A microprocessor is the most complex manufactured product on earth. In fact, it takes hundreds of steps and only the most important ones have been visualized in this picture story.

During this final test the processors will be tested for their key characteristics (among the tested characteristics are power dissipation and maximum frequency).

Based on the test result of class testing processors with the same capabilities are put into the same transporting trays. This process is called "binning". Binning determines the maximum operating frequency of a processor, and batches are divided and sold according to stable specifications.

The manufactured and tested processors (again Intel Core i7 processor is shown here) either go to system manufacturers in trays or into retail stores in a box. Many thanks to Intel for supplying the text and photos in this picture story. Check out Intel's site for full size images of this entire process