HARD DRIVES
What does a hard drive do?
Storage is the hard drive’s responsibility. Everything you keep on your computer is on a hard drive. Not just documents, pictures, music, and videos. Your programs, your preferences, even your operating system—they’re all stored on your computer’s hard drive.
How big of a hard drive do you need?
Everything that can be saved on a hard drive is measured in terms of its size. Text is very small, pictures are larger, music is even bigger, and video is the biggest of the bunch. A drive is like a scale; it measures things in terms of bytes (B), kilobytes (KB), megabytes (MB), gigabytes (GB), and terabytes (TB.) Roughly speaking, a megabyte is 1 million bytes, a gigabyte is 1 billion bytes, and a terabyte is 1 trillion bytes.
A hard drive will work with either a PC or Mac. It just depends on the connection type.There are several different ways to connect your hard drive to your computer:
referred to as Parallel ATA or PATA, so that it is not confused with the newer Serial ATA (SATA) interface. ATA is also often called IDE (Integrated Drive Electronics).
What does a hard drive do?
Storage is the hard drive’s responsibility. Everything you keep on your computer is on a hard drive. Not just documents, pictures, music, and videos. Your programs, your preferences, even your operating system—they’re all stored on your computer’s hard drive.
How big of a hard drive do you need?
Everything that can be saved on a hard drive is measured in terms of its size. Text is very small, pictures are larger, music is even bigger, and video is the biggest of the bunch. A drive is like a scale; it measures things in terms of bytes (B), kilobytes (KB), megabytes (MB), gigabytes (GB), and terabytes (TB.) Roughly speaking, a megabyte is 1 million bytes, a gigabyte is 1 billion bytes, and a terabyte is 1 trillion bytes.
A hard drive will work with either a PC or Mac. It just depends on the connection type.There are several different ways to connect your hard drive to your computer:
- USB
This is the most common connection type. There’s no setup at all. Just plug it in. The computer recognizes the drive, and you’re able to read and save files almost instantly. - Firewire
Plug-and-play like USB, Firewire 800 is significantly faster, making it popular with those transferring video files. - SATA
This is the standard connection for internal hard drives. Offers the highest file transfer speeds of any format. - eSATA
A less-common, high-performance connection most commonly found in PCs. An eSATA connection performs at speeds that most closely resemble an internal drive. - AT Attachment (ATA)
referred to as Parallel ATA or PATA, so that it is not confused with the newer Serial ATA (SATA) interface. ATA is also often called IDE (Integrated Drive Electronics).
Integrated circuits work such that the memory is stored in the capacitance of the transistor so charge must be present in order to refresh the data every few milliseconds. This is why Random access memory is volatile; that is, it stores data as long as the computer is on but loses the data stored when the computer turns off. Modern memory chips are integrated circuits which are miniature circuits made of the semiconductor silicon in a process called the Metal oxide semiconductor process. These circuits began with very simple designs and containing only a few transistors but have been improved so that we now have integrated circuits containing billions of transistors. The two main forms of modern RAM are static RAM (SRAM) and dynamic RAM (DRAM). In SRAM, a bit of data is stored using the state of a six transistor memory cell. This form of RAM is more expensive to produce, but is generally faster and requires less power than DRAM and, in modern computers, is often used as cache memory for the CPU. DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a DRAM memory cell. The capacitor holds a high or low charge (1 or 0, respectively), and the transistor acts as a switch that lets the control circuitry on the chip read the capacitor's state of charge or change it. As this form of memory is less expensive to produce than static RAM, it is the predominant form of computer memory used in modern computers. However, both forms are still volatile.
Several new types of non-volatile RAM, which will preserve data while powered down, are under development. The technologies used include carbon nanotubes and approaches utilizing the magnetic tunnel effect. Amongst the 1st generation MRAM, a 128 KiB (128 × 210 bytes) magnetic RAM chip was manufactured with 0.18 µm technology in the summer of 2003. In June 2004, Infineon Technologies unveiled a 16 MiB (16 × 220 bytes) prototype again based on 0.18 µm technology. There are two 2nd generation techniques currently in development: Thermal Assisted Switching (TAS) which is being developed by Crocus Technology, and Spin Torque Transfer (STT) on which Crocus, Hynix, IBM, and several other companies are working.
The main function of RAM is to be a storage location for data and a source for components which need to access this data in order to carry out their duties. An example of this is when the user tries to run a program, the data necessary is transferred from storage to RAM and is then transferred to the CPU to be processed and carried out. AS such, it can be said that RAM holds the data that is presently being used by the CPU and the data for programs being run. RAM also has other ways in which it is used, for example:
1. Most modern operating systems employ a method of extending RAM capacity, known as virtual memory. A portion of the computer's hard drive is set aside for a paging file or a scratch partition, and the combination of physical RAM and the paging file form the system's total memory. When the system runs low on physical memory, it can swap portions of RAM to the paging file to make room for new data, as well as to read previously swapped information back into RAM. Excessive use of this mechanism results in thrashing and generally hampers overall system performance, mainly because hard drives are far slower than RAM. 2. Software can partition a portion of a computer's RAM, allowing it to act as a much faster hard drive that is called a RAM disk. A RAM disk loses the stored data when the computer is shut down, this is unless memory is arranged to have a standby battery source. 3. Sometimes, the contents of a relatively slow ROM chip are copied to read/write memory to allow for shorter access times. The ROM chip is then disabled while the initialized memory locations are switched in on the same block of addresses (often write-protected). This process, sometimes called shadowing, is fairly common in both computers and embedded systems. Free memory is reduced by the size of the shadowed ROMs. |
Memory Chips are integrated circuits that are made of the semiconductor silicon in the MOS process. These chips are placed on the PCB which makes up the motherboard. The motherboard is produced on the Surface Mount Technology lines (SMT lines). This is done by passing the PCB through a group of machines which each have a specific purpose. This begins with the PCB having solder placed on it a specific solder points. The solder is passed through a metal stencil with specially placed holes onto the PCB. The next machine then checks to ensure that the solder placed is the right amount and contains no impurities or contaminations. Next, small components are placed on the board at their appropriate places. These components are resistors and capacitors, for example. This is followed by the placement of the primary components on the board, things such as memory chips. Then the board is heated based on the design specifications. The heating is done in a 7 temperature cycle of up to 500 degrees Fahrenheit for the purpose of melting the solder so that the components will be properly attached to the board. Now the PCBs are carried through a second visual check to ensure that the components are all placed in their correct spots on the board. They are then labeled with when and where they were produced as well as the components used. The excess edges of the boards are then cut off in a high RPM machine before they are sent to the testing phase of production.
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RAM works in relation to storage such that when a program that resides in storage is called to be run, it is transferred from storage to RAM first. This allows for the program to be run faster as the access time of RAM is far superior to that of storage. As such, the overall performance of the computer is increased. There is also interaction if there is not enough RAM to manage the programs being run, this interaction is the Virtual Memory function of RAM. This allows for virtual memory space to be created on storage so as to accommodate the programs the user is trying to run. This does mean that the performance will not be as efficient during this time. The Ram chips are located on the motherboard along with the other various components. Random access memory works with the Central Processing Unit when the user requests an application; after the data is transferred from storage to RAM then it is moved to the CPU to be processed. This is a very relevant relationship in the total running of the computer.