NT1110 Computer Structure and Logic
Unit 7 Research Paper
CMOS runs on about a millionth of an amp of electrical current. This efficiency allows it to store configuration data for a long time (maybe years), powered only from either low-voltage dry cell or lithium batteries. On newer PCs, the CMOS battery is located on the motherboard. On older systems, like the Amstrad 1512, a pair of AA batteries mounted on the top of the system powered the CMOS.
The function of CMOS RAM is to store information your computer needs when it boots up, such as hard disk types, keyboard and display type, chip set, and even the time and date. If the battery that powers your CMOS RAM dies, all this information is lost, and your PC will boot with the default information that shipped with the motherboard. In most cases, this means you´ll have no access to your hard disks until you supply CMOS with the necessary information. Without access to your hard disks, you won´t be able to boot your operating system.
CMOS stands for Complementary Metal Oxide Semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. CMOS technology is also used for several analog circuits such as image sensors (CMOS sensor), data converters, and highly integrated transceivers for many types of communication. Frank Wanlass patented CMOS in 1967 (US patent 3,356,858). CMOS is also sometimes referred to as complementary-symmetry metal–oxide–semiconductor (or COS-MOS).The words "complementary-symmetry" refer to the fact that the typical digital design style with CMOS uses complementary and symmetrical pairs of p-type and n-type metal oxide semiconductor field effect transistors (MOSFETs) for logic functions.
Two important characteristics of CMOS devices are high noise immunity and low static power consumption. Significant power is only drawn when the transistors in the CMOS...