SECTION A (40 Marks)
Answer ALL the questions in this section.
1. Distinguish between monoprogramming and multiprogramming memory addressing as used in operating systems.
Answer:
Monoprogramming memory addressing refers to a single process running at a time, with all memory allocated to that process.
Multiprogramming memory addressing allows multiple processes to reside in memory at the same time, switching between them to optimize CPU usage.
2. Explain each of the following terms as used in operating systems:
(a) Kernel (2 marks)
(b) Shell (2 marks)
(c) Dispatcher (2 marks)
Answer:
Kernel: The core component of an operating system that manages system resources and allows communication between hardware and software.
Shell: The interface that allows users to interact with the operating system, either through a command-line interface (CLI) or a graphical user interface (GUI).
Dispatcher: A component of the operating system’s scheduler that assigns processes to the CPU for execution.
3. Explain each of the following memory design requirements used in operating systems:
(a) Coherency (2 marks)
(b) Locality of reference (2 marks)
Answer:
Coherency: Ensuring that multiple copies of data in different caches are consistent across a multi-core or multiprocessor system.
Locality of reference: Refers to the tendency of programs to access a relatively small portion of the address space during a specific time period, improving memory efficiency.
4. Describe each of the following terms as used in operating systems:
(a) Reentrant loader (2 marks)
(b) Job control language (2 marks)
Answer:
Reentrant loader: A type of program loader that can be interrupted and reentered while it is running.
Job control language (JCL): A language used to describe jobs (tasks) to the operating system, especially in batch processing systems.
5. Distinguish between hard errors and soft errors as used in memory management. (4 marks)
Answer:
Hard errors are permanent hardware failures in memory, typically caused by physical defects.
Soft errors are temporary, non-destructive errors in memory caused by environmental factors, such as cosmic rays or electrical interference.
6. Ruby recommended the inclusion of RAID technology for data storage. Explain the advantages that this system would provide. (4 marks)
Answer:
RAID (Redundant Array of Independent Disks) provides advantages such as data redundancy (protecting against disk failure), improved data integrity, and faster data access through striping and mirroring techniques.
7. Explain the function of each of the following types of computer memories:
(a) Cache memory (2 marks)
(b) Virtual memory (2 marks)
Answer:
Cache memory: A small, high-speed memory located close to the CPU, used to store frequently accessed data to speed up processing.
Virtual memory: A memory management technique that uses disk storage to simulate additional RAM, allowing a system to handle larger workloads than the physical memory allows.
8. Carmine noted that most of the software she bought came on CD-ROM. Justify this trend, giving two reasons. (4 marks)
Answer:
CD-ROMs provide a durable, portable medium for distributing software.
They are cost-effective for mass production, and many computers come with CD-ROM drives for easy installation of software.
9. Distinguish between static RAM and dynamic RAM as used in memory management. (4 marks)
Answer:
Static RAM (SRAM): Faster and more expensive, stores data in flip-flops, and does not need to be refreshed periodically.
Dynamic RAM (DRAM): Slower and cheaper, stores data in capacitors, and needs to be refreshed periodically to retain information.
10. Define each of the following terms as used in file management:
(a) Relative path (2 marks)
(b) Absolute path (2 marks)
Answer:
Relative path: A file path that is relative to the current directory or location in the file system.
Absolute path: A file path that starts from the root directory and specifies the complete location of a file or folder.
11. (a) With the aid of a diagram, describe paged memory management technique. (6 marks)
(b) Most computer users prefer USB flash memory to compact disks for use as storage media. Explain three reasons for this emerging trend. (6 marks)
(c) With the aid of an example, describe the term device driver as used in operating systems. (6 marks)
Answer:
(a) Paged memory management is a memory management scheme that eliminates the need for contiguous allocation of physical memory. The memory is divided into fixed-size pages, and these pages are loaded into any available memory frames. This improves memory utilization and eliminates fragmentation.
(b)
Portability: USB flash drives are smaller and more portable than CDs.
Storage capacity: Flash drives generally offer higher storage capacities compared to CDs.
Reusability: Flash drives can be written and rewritten multiple times, whereas CDs are usually read-only or limited in rewritability.
(c) A device driver is a specialized software that enables the operating system to communicate with hardware devices. For example, a printer driver allows the OS to send print jobs to the printer.
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