Computer Fundamentals and System Concepts

Linux has a robust security architecture that makes it less vulnerable to malware compared to Windows, so antivirus software is not mandatory. However, it can be optionally used, especially in mixed environments or when sharing files with Windows systems. The option that antivirus doesn't exist for Linux is false, and the extremes of mandatory or completely unnecessary are both incorrect.

The Intel 4004, released in November 1971, was the world's first commercially available microprocessor. It was a 4-bit processor designed for a Japanese calculator company (Busicom) and contained 2,300 transistors on a single chip. The 4040 and 8008 were later improved models, but the 4004 was the groundbreaking first.

The AVR microcontroller family, developed by Atmel (now Microchip), was one of the first to feature on-chip flash memory for program storage. This made it revolutionary compared to contemporary options like the 8051 (which typically used external ROM/EPROM) and early PIC microcontrollers (which used EPROM). The flash memory allowed for easy reprogramming without UV erasure.

PL/I stands for Programming Language One, not Peripheral Listing/Index. It is a procedural programming language developed by IBM in the 1960s for scientific, engineering, and business applications. The other definitions of offline, online, and programs are essentially correct.

PC stands for Personal Computer. This term became popular in the 1980s with the IBM PC to describe computers designed for individual use. 'Private Computer', 'Professional Computer', and 'Personal Calculator' are incorrect expansions of the acronym.

First-generation computers (1940s-1950s) used vacuum tubes for electronic switching and amplification. These large, heat-generating devices were eventually replaced by smaller, more reliable transistors in second-generation systems. The ENIAC, a famous first-generation computer, contained over 17,000 vacuum tubes.

In 2006, Apple began transitioning from PowerPC to Intel processors. The first Intel-based Macs were the MacBook Pro and iMac announced in January 2006. The MacBook followed later in May.

IBM's mainframe computer code-named 'T-Rex' was released during the 2003-2005 period as part of their zSeries server line. The T-Rex codename represented the power and dominance of IBM's mainframe technology in enterprise computing. Other options like Saber, Mamath, and Swordfish are not associated with IBM mainframe releases from this era.

NetBIOS (Network Basic Input/Output System) is indeed a networking protocol developed by Microsoft and IBM for local area networks. It allows applications on different computers to communicate and access resources on the network. The other options (Applications, Desktop, Server) are not the primary domain NetBIOS serves.

The question asks for possible causes of a system slowdown when no configuration changes have been made. Among the options, a virus or malware infection (option C) is the most likely cause of sudden, unexplained performance degradation without user-initiated changes. While too many installed programs, old hardware, or a slow processor can cause slowness, these are chronic issues not "recent" changes. A virus can suddenly consume resources and slow the system.

An active virus typically shows high CPU usage as it runs malicious processes in the background. Legitimate viruses usually run under the user's context (your username) rather than the System process, though sophisticated malware can disguise itself. Memory consumption is not a definitive indicator as legitimate programs can also use high memory. Task Manager's Processes tab helps identify suspicious processes running under your user account with unusual CPU usage.

When a computer doesn't switch on at all, the issue is typically with power delivery or the motherboard. SMPS (Switched Mode Power Supply) provides power to all components, and if it fails, nothing receives power. A faulty motherboard can also prevent the system from starting. Hard disk and RAM issues usually allow the computer to power on but fail to boot properly.

When a system starts but shows no display, RAM or motherboard issues are most likely. RAM problems prevent the system from completing POST, while motherboard failures can affect the GPU or display output. Storage devices like CD ROM and hard disk don't impact the display signal.