Методическое пособие по совершенствованию навыков чтения и говорения на английском языке для студентов фксиС и фитиУ
английский для ИТ 1
- Бұл бет үшін навигация:
- RDRAM (Rambus dynamic RAM
- “hard-wired”
- ROM BIOS (basic input/output system
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Another sequence of charged capacitors represents the letter “C” |
Fig. 1: The way RAM represents different characters
In some respects, RAM is similar to a chalkboard. You can use a chalkboard to write mathematical formulas, erase them, and then write an outline for a report. RAM contents can be changed just by changing the charge of the capacitors. Unlike disk storage, most RAM is volatile, which means it requires electrical power to hold data. If the computer is turned off or the power goes out, all data stored in RAM instantly and permanently disappears.
Today’s personal computer operating systems are quite adept at allocation RAM space to multiple programs. If a program exceeds its allocated space, the operating system uses an area of the hard disk, called virtual memory, to store parts of programs or data files until they are needed. By selectively exchanging the data in RAM with the data in virtual memory, your computer effectively gains almost unlimited memory capacity.
RAM components vary in speed, technology, and configuration. RAM speed is often expressed in nanoseconds or megahertz. One nanosecond (ns) is 1 billionth of a second. RAM speed can also be expressed in MHz (millions of cycles per second). Most of today’s personal computers use SDRAM (synchronous dynamic RAM), fast and relatively inexpensive, it is typically available on a small circuit board called a DIMM (dual inline memory module) or RDRAM (Rambus dynamic RAM), first developed for a game system and then adapted for use in personal computers.
Read-Only Memory
ROM (read-only memory) is a type of memory circuitry that holds the computer’s startup routine. Whereas RAM is temporary and volatile, ROM is permanent and non-volatile. ROM circuitry holds “hard-wired” instructions that are a permanent part of the circuitry and remain in place even when the computer power is turned off.
When you turn on your computer, the microprocessor receives electrical power and is ready to begin executing instructions. As a result of the power being off, however, RAM is empty and doesn’t contain any instructions for the microprocessor to execute. Now ROM plays its part. ROM contains a small set of instruction called the ROM BIOS (basic input/output system).These instructions tell the computer how to access the hard disk, find the operating system, and load it into RAM. After the operating system is loaded, the computer can understand your input, display output, run software, and access your data.
CMOS Memory
To operate correctly, a computer must have some basic information about storage, memory, and display configurations. The information is held in CMOS (pronounced “SEE moss”), a type of chip that requires very little power to hold data. It can be powered by a small battery that is integrated into the system board and automatically recharges while your computer power is on. The battery trickles power to the CMOS chip so that it can retain vital data about your computer system configuration even when your computer is turned off. When you change the configuration of your computer system, the data in CMOS must be updated.
The more data and programs that can fit into RAM, the less time your computer will spend moving data to and from virtual memory.
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