2--x86 Processor

Digital displays generally display sharper text than

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Unformatted text preview: res electrons from the left side to the right in a horizontal row, briefly turns off, and returns to the left side of the screen to begin a new row. Horizontal retrace refers to the time period when the gun is off between rows. When the last row is drawn, the gun turns off (called the vertical retrace) and moves to the upper left corner of the screen to start over. A direct digital Liquid Crystal Display (LCD) panel, considered standard today, receives a digital bit stream directly from the video controller and does not require raster scanning. Digital displays generally display sharper text than analog displays. 2.4.3 Memory Several basic types of memory are used in Intel-based systems: read-only memory (ROM), erasable programmable read-only memory (EPROM), dynamic random-access memory (DRAM), static RAM (SRAM), video RAM (VRAM), and complimentary metal oxide semiconductor (CMOS) RAM: • ROM is permanently burned into a chip and cannot be erased. • EPROM can be erased slowly with ultraviolet light and reprogrammed. • DRAM, commonly known as main memory, is where programs and data are kept when a program is running. It is inexpensive, but must be refreshed every millisecond to avoid losing its contents. Some systems use ECC (error checking and correcting) memory. • SRAM is used primarily for expensive, high-speed cache memory. It does not have to be refreshed. CPU cache memory is comprised of SRAM. • VRAM holds video data. It is dual ported, allowing one port to continuously refresh the display while another port writes data to the display. • CMOS RAM on the system motherboard stores system setup information. It is refreshed by a battery, so its contents are retained when the computer’s power is off. 2.4.4 Input-Output Ports and Device Interfaces Universal Serial Bus (USB) The Universal Serial Bus port provides intelligent, high-speed connection between a computer and USB-supported devices. USB Version 2.0 supports data transfer speeds of 480 megabits pe...
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This note was uploaded on 11/29/2013 for the course CSE 451 taught by Professor Hussein during the Winter '13 term at Fatih Üniversitesi.

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