Computer Performance & Storage Devices

Computer Performance

Boot Process Sequence of events that occurs between the time you turn on a computer and the time that it becomes ready to accept commands. Purposes Runs a diagnostic test to make sure everything is working. Loading the operating system, so the computer can carry out basic operations.

6 events of the boot process: Power up Start boot program Power-on self-test Identify peripheral devices Load operating system Check configuration and customization

Circuits The path from one component of a computer to another that data uses to travel. Circuits run between RAM and the microprocessor RAM and various storage devices

Silicon Chip Silicon is melted sand. What the circuits are embedded into to keep them together.

Megahertz (mHz) A measurement used to describe the speed of the system clock. A megahertz is equal to one million cycles (or pulses) per second. 1.3 GHz means that the microprocessor’s clock operates at a speed of 1.3 BILLION cycles per second.

RAM vs. ROM RAM ROM “Random Access Memory” The ability of a storage device to go directly to a specific storage location without having to search sequentially from a beginning location. Very volatile Cannot hold data when the power is off. Looses all data when power is lost. ROM “Read only memory” Drives can read data from disks, but cannot store new data on them. One or more integrated circuits that contain permanent instructions that the computer uses during the boot process.

Binary Number System A method for representing letters or numbers using only two digits, 0 and 1. Bit Each 0 or 1 Byte 8 bits Also referred to as Base 2 Binary Code.

Memory Measurements Petabyte Bit Byte Kilobyte Megabyte Gigabyte Each 0 or 1 Byte 8 bits Kilobyte Approximately 1,000 bytes Exactly 1,024 bytes Megabyte Approximately 1 million bytes Exactly 1,048,576 bytes Gigabyte Approximately 1 billion bytes Terabyte Approximately 1 trillion bytes or 1024 gigabytes Petabyte 1024 Terabytes

Storage Devices Used to keep data when the power to the computer is turned off. Medium/media Location where data is stored.

Hard Disk Usually mounted inside the computer’s system unit. Can store billions of characters of data. Stated in forms of bytes: Gigabytes, Terabytes or Petabytes

USB or Flash Drive A flash memory card that plugs into the computer's USB port. Small enough to hook onto a keychain, it emulates a small disk drive and allows data to be easily transferred from one machine to another.  Also known as a "flash drive," "pen drive," "keychain drive," "key drive," "USB key," "USB stick" and "memory key," numerous brand names have also been coined such as Lexar's JumpDrive and Trek 2000 International's ThumbDrive. 

Portable Hard drive A disk drive that is plugged into an external port on a computer such as USB. Typically used for backup, but also as secondary storage, such units rival internal drives in capacity. For laptops, the PC Card slot may be used to connect a cable to a full-size drive, or the hard disk may be contained entirely inside the PC Card.

CD-ROM “CD – Read Only Memory” Also called CD-R Storage device that uses laser technology to read data that is permanently stored on compact disks, cannot be used to write data to a disk.

CD-RW “CD-Read Write” A storage device that reads data from CD’s and also can write data to CD’s. Similar to a CD-ROM, but has the ability to write to CD.

DVD-ROM “Digital Video Disks – Read Only Memory” Reads data from CD’s (audio and data) and DVD’s (data or movie) Cannot be used to write data to a disk.

Resources Parsons, June Jamrich, and Dan Oja. Computer Concepts. Boston: Course Technology - Thompson Learning, 2002.