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System Memory Memory is a large array of words or bytes, each with its own address. It is a repository of quickly accessible data shared by the CPU and I/O devices. Main memory is a volatile storage device. Built up using Dynamic RAM (DRAM) Synchronous DRAM
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System Memory • Memory is a large array of words or bytes, each with its own address. It is a repository of quickly accessible data shared by the CPU and I/O devices. • Main memory is a volatile storage device. Built up using Dynamic RAM (DRAM) Synchronous DRAM • Primary cache (Level 1) is on the CPU • Secondary cache (Level 2) supplies stored info to processor without any delay
SecondaryStorage Management • Since main memory (primary storage) is volatile and too small to accommodate all data and programs permanently the computer system must provide secondary storage to back up main memory. • Most modern computer systems use disks as the principle online storage medium, for both programs and data. • CD-ROM can be recordable/rewritable • DVD large capacity successor to the CD • Tape Backup • Removable Storage
Microprocessor (CPU) • John von Neumann’s architecture: Central Arithmetic unit, Central Control unit, Memory, I/O devices • All the elements of a CPU (registers, ALU, primary cache, execution unit,..) stay in step by a clock which dictates how fast it operates • Pipelining: at any one time one instruction is being loaded, while an other is being executed
COMPONENTS • Motherboards • Processors • Chipsets • Interfaces • System Memory (main memory), others • Primary cache (CPU) • Secondary cache (bridge processor-memory)
Interfaces • Buses • Fastest bus connects primary cache with CPU chip • Dual independent (memory and level 2 cache) • ISA bus: I/O Bus system • Expansion bus for additional components • PCI bus: Local Bus standard • Accelerated Graphics Port (AGP): Frontside bus
Motherboard • Main circuit board • Input/Output System (BIOS) in ROM • The Baby AT (BAT) format reduced the dimensions of the motherboard • Intel Advanced/ML (ATX) • LPX is a specialized Baby-AT used in low profile, loose spec desktop PCs • NLX is Intel’s improved LPX