In a microprocessor based system, why does the design typically include ROM chips alongside the microprocessor and RAM, and what is the main purpose of these ROM devices?

Introduction / Context:
Microprocessor based systems use several types of memory, each with a different role. Random Access Memory is used for temporary data and code during execution, while Read Only Memory is used for permanent or semi permanent data and programs. This question asks why ROM chips are included in such systems and what their primary function is in relation to the microprocessor and overall system startup.

Given Data / Assumptions:

- We have a microprocessor, RAM, and ROM in the system.- We assume typical scenarios such as personal computers or embedded systems.- The question focuses on the main purpose of ROM chips.

Concept / Approach:
ROM stands for Read Only Memory. It is nonvolatile, meaning its contents are retained when power is off. In microprocessor systems, ROM stores firmware such as the Basic Input Output System in PCs or monitor programs and bootloaders in embedded systems. When the processor resets, it begins executing instructions from a fixed address that usually maps into ROM, allowing the system to initialise hardware and load an operating system or main application. RAM, by contrast, loses its contents when power is removed and is not suitable for storing the code that must be present at startup.

Step-by-Step Solution:
Step 1: Recall that firmware is software that is closely tied to hardware and stored in nonvolatile memory.Step 2: In a PC, the BIOS stored in ROM or flash memory provides the initial instructions for system startup and basic hardware control.Step 3: In many embedded systems, ROM stores the main program that the microprocessor executes immediately after reset.Step 4: Option A states that ROM is used to store firmware like BIOS or monitor programs that must remain even when power is off, which exactly describes this role.Step 5: Option B claims ROM provides additional temporary working space, which contradicts its read only and nonvolatile nature. Temporary working space is provided by RAM.Step 6: Option C suggests ROM acts as a faster alternative to CPU registers for arithmetic, which is incorrect because ROM access is generally slower and not used like a register file.Step 7: Option D restricts ROM to graphics image storage only, which is far too narrow and not the main reason systems include ROM chips.Step 8: Option E claims ROM replaces hard disks, which is not accurate in general purpose computers where disks or solid state drives still store user data and operating systems.

Verification / Alternative check:
System block diagrams in textbooks show the microprocessor fetching its first instruction from ROM after reset. BIOS update utilities and embedded firmware programmers target nonvolatile memory devices because they need to preserve code across power cycles. These practical examples confirm that the core function of ROM is to hold firmware that enables system startup and hardware control, as described in option A.

Why Other Options Are Wrong:
Option B confuses RAM and ROM roles. Option C misunderstands how registers and memory are used in computation. Option D describes a possible specialised use of ROM but not its typical primary purpose. Option E overstates ROM capabilities in general personal computers, where it does not fully replace mass storage devices.

Common Pitfalls:
Some learners treat all memory as interchangeable and forget that volatility and write capability matter. Remember that ROM keeps code safe when power is off but is not typically used for dynamic data during normal program execution. Keeping a clear mental distinction between RAM for temporary data and ROM for permanent firmware helps in understanding system design.

Final Answer:
Microprocessor based systems include ROM chips mainly to store firmware such as BIOS or monitor programs that must remain available at power up, as in option A.