CHAPTER 3 – INFORMATION TECHNOLOGY CONCEPTS
Computer hardware must be carefully selected to meet the evolving needs of the
organization and its supporting information systems. Computer hardware should
be selected to meet specific user and business requirements. These requirements
can evolve and change over time. The central processing unit (CPU) and memory
cooperate to execute data processing. The CPU has three main components: the
arithmetic/logic unit (ALU), the control unit, and the register areas. Instructions
are executed in a twophase process called a machine cycle that includes the
instruction phase and the execution phase. Computer system processing speed is
affected by clock speed, which is measured in gigahertz (GHz). As the clock speed
of the CPU increases, heat is generated that can corrupt the data and instructions
the computer is trying to process. Bigger heat sinks, fans, and other components
are required to eliminate the excess heat. This excess heat can also raise safety
issues.
Primary storage, or memory, provides working storage for program instructions
and data to be processed and provides them to the CPU. Storage capacity is
measured in bytes. A common form of memory is random access memory (RAM).
RAM is volatile; loss of power to the computer erases its contents. RAM comes in
many different varieties including dynamic RAM (DRAM), synchronous DRAM
(SDRAM), Double Data Rate SDRAM, and DDR2 SDRAM. Read-only memory
(ROM) is nonvolatile and contains permanent program instructions for execution
by the CPU. Other nonvolatile memory types include programmable read-only
memory (PROM), erasable programmable read-only memory (EPROM),
electrically erasable PROM, and flash memory.
Cache memory is a type of high-speed memory that CPUs can access more rapidly
than RAM. A multicore microprocessor is one that combines two or more
independent processors into a single computer so they can share the workload.
Intel and AMD have introduced quad-core processors that are effective in working
on problems involving large databases and multimedia. Parallel computing is the
simultaneous execution of the same task on multiple processors to obtain results
faster. Massively parallel processing involves linking many processors to work
together to solve complex problems. Grid computing is the use of a collection of
computers, often owned by multiple individuals or organizations, to work in a
coordinated manner to solve a common problem.
Computer systems can store larger amounts of data and instructions in secondary
storage, which is less volatile and has greater capacity than memory. The primary
characteristics of secondary storage media and devices include access method,
