Week 6: Memory Management: Fixed partitions

Question 1

What does the process manager determine?

Answer 1

When a process will run

Question 2

What does the memory manager determine?

Answer 2

Where a process will run.

Question 3

What is the “first law” of computing?

Answer 3

However much memory a computer has, a program will be written that needs more.

Question 4

What are the three main types of computer memory?

Answer 4

• Cache (fastest, on or near the processor)
• Primary memory (RAM/ROM)
• Secondary memory (hard disks or offline storage).

Question 5

How does memory speed compare between types?

Answer 5

• Cache is accessed in nanoseconds
• Primary memory in a few nanoseconds, and
• Hard disks in milliseconds.

Question 6

Why can’t all memory be cache?

Answer 6

Cache memory is expensive and limited in size due to economic and design constraints.

Question 7

How does primary memory differ from secondary memory?

Answer 7

Primary memory is directly addressable by the processor, while secondary memory requires data transfer to primary memory for use.

Question 8

In the simplest memory model, how is memory allocated?

Answer 8

One process is loaded into memory at a time and uses as much memory as needed.

Question 9

What technique can increase memory availability in a simple model?

Answer 9

Using overlays to load portions of a program as needed.

Question 10

What is contiguous storage allocation?

Answer 10

Memory is allocated in a single, continuous block with no gaps.

Question 11

What is non-contiguous storage allocation?

Answer 11

Memory is allocated in multiple blocks or segments that may be scattered in primary memory.

Question 12

How does multiprogramming improve processor utilization?

Answer 12

By running multiple processes, the processor can stay busy even when one process is waiting for I/O.

Question 13

How does fixed partition multiprogramming work?

Answer 13

Memory is divided into fixed-size partitions, which may vary in size and are allocated to processes as needed.

Question 14

What does the operating system track in fixed partitions?

Answer 14

Which partitions are in use and which are free.

Question 15

What is the downside of multiple partition queues?

Answer 15

Memory can be wasted when large partitions are empty while small jobs wait.

Question 16

How does a single queue address multiple partition queues issue and what is the downside of this approach?

Answer 16

A single queue reduces wasted memory but may still lead to inefficiencies with small jobs in large partitions.

Question 17

What does address binding involve?

Answer 17

Assigning memory addresses to data and instructions, such as connecting a function call to its library implementation.

Question 18

Why is address binding complex in multiprogramming?

Answer 18

The specific memory location of a process is not known beforehand, requiring relocation solutions.

Question 19

What is the relocation problem?

Answer 19

Memory addresses need to adapt based on where a process is loaded in memory.

Question 20

How can relocation be handled dynamically?

Answer 20

By using base (or segment) registers to calculate addresses relative to a program’s starting point.

Question 21

What happens when a process is moved in memory?

Answer 21

The base register is updated, and all address calculations automatically adjust.

Question 22

How is memory protection enforced?

Answer 22

Using a limit register along with a base register to ensure memory access stays within valid bounds.

Question 23

What happens if a memory address exceeds the limit?

Answer 23

An error occurs, preventing access to unauthorized memory.