Chapter 1: Hardware

 Hardware is one of six domains in the CompTIA A+ Exams. It is a major piece of both exams. Hardware accounts for 27 percent of the 220-701 Essentials Exam and 38 percent of the 220-702 Practical Applications Exam.

CPUs

The Central Processing Unit (CPU) is the main processing unit of the personal computer (PC). It has an integral relationship with the motherboard and the system memory. These three devices control the data-processing aspect of the PC. Drives handle data storage, and input/output (I/O) interfaces allow human interaction, communication with peripherals, and network communication.

RISC Versus CISC

Most general purpose PCs use a complex instruction set chip (CISC). Many dedicated computers used in data collection, sensors, routers, and graphics processors are reduced instruction set chips (RISC). These two types of processors can complete the same tasks, but if the computer is processing the same kind of data all the time, it is often more efficient to reduce the amount of possible instructions the CPU can execute. This makes the decision-making process simple and quick.

32-Bit Versus 64-Bit CPUs

32-bit processors are slowly being replaced by 64-bit processors as an increasing number of applications and operating systems (OS) support them. You should use a 64-bit OS and applications on a 64-bit CPU to get the full benefit of increased performance. Most 64-bit applications are backward compatible and will work on 32-bit CPUs.

Clock Rate

The actual speed of the CPU is governed by a BIOS setting called the clock rate. CPUs run in a range of speeds, not just one specific speed. Increasing the speed is called over clocking. It improves performance, but it comes at a cost. The faster the CPU runs, the hotter it gets. If it gets too hot, the BIOS shuts down the CPU. If the temperature thermocouple is not correctly reading the CPU heat, the CPU can actually melt or catch fire. More sophisticated motherboards throttle down the CPU speed in the event it gets too hot to prevent entirely shutting down the computer.

Cores and Cache

CPUs traditionally contain only one core. Some server and workstation motherboards can support multiple CPUs (multiprocessor). More commonly, you can find PCs with one CPU that includes two or four cores (dual or quad core, respectively) Multicore is not the same as multiprocessor. Multiple cores allow the PC to simultaneously process multiple tasks (threads).