Deck 2: Memory Management: Early Systems

Question 1

A large job can have problems with a first-fit memory allocation list.

Answer 1

True

Question 2

One of the problems with the best-fit algorithm is that the entire table must be searched before the allocation can be made because the memory blocks are physically stored in sequence according to their location in memory.

Answer 2

True

Question 3

The fixed partition scheme does not require that the entire program be stored contiguously and in memory from the beginning to the end of its execution.

Answer 3

False

Question 4

The problem of partition intrusion is present in single-user contiguous allocation schemes.

Question 5

A null entry in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list.

Question 6

The first-fit algorithm assumes that the Memory Manager keeps only one list containing free memory blocks.

Question 7

In the relocatable dynamic partitions scheme, the Memory Manager relocates programs to gather together all of the empty blocks and compact them to make one block of memory large enough to accommodate some or all of the jobs waiting to get in.

Question 8

In a fixed partition scheme, large jobs may have a longer turnaround time as they wait for free partitions of sufficient size or may never run.

Question 9

A single-user system supports multiprogramming.

Question 10

The best-fit free list scheme uses memory more efficiently than the first-fit free scheme but it is slower to implement.

Question 11

The best-fit allocation method keeps the free/busy lists organized by memory locations, low-order memory to high-order memory.

Question 12

Early memory management schemes are still used in today's operating systems.

Question 13

The first step in loading a job in a single-user system is storing the first memory location of program into the base register (for memory protection).

Question 14

To overlay is to transfer segments of a program from main memory into secondary storage for execution, so that two or more segments take turns occupying the same memory locations.

Question 15

Research continues to focus on finding the optimum allocation scheme.

Question 16

The algorithm used to store jobs into memory requires a few more steps than the one used for a single-user system because the size of the job must be matched with the size of the partition to make sure it fits completely.

Question 17

All computers have only a finite amount of memory and if a program doesn't fit, then either the size of the main memory must be increased or the program must be modified.

Question 18

For a fixed partition system, memory deallocation is quite complex.

Question 19

The fixed partition scheme works well if all of the jobs run on the system are of the same size or if the sizes are known ahead of time and don't vary between reconfigurations.

Question 20

The first attempt to allow for multiprogramming used fixed partitions.

Question 21

In a single-user system, jobs are processed ____.

A) sequentially
B) intermittently
C) randomly
D) in order of longest job to shortest job

Question 22

The following algorithm can be described as ____. 1 Initialize memory_block(0) = 99999
2 Compute initial_memory_waste = memory_block(0) - job_size
3 Initialize subscript = 0
4 Set counter to 1
5 Do while counter <= number of blocks in memory
If job_size > memory_size(counter)
Then counter = counter + 1
Else
Memory_waste = memory_size(counter) - job_size
If initial_memory_waste > memory_waste
Then subscript = counter
Initial_memory_waste = memory_waste
Counter = counter + 1
End do
6 If subscript = 0
Then put job in waiting queue
Else
Load job into memory_size(subscript)
Adjust free/busy memory lists
7 Go fetch next job

A) first-fit memory allocation
B) best-fit memory allocation
C) least-fit memory allocation
D) fixed partition memory allocation

Question 23

In the algorithm to load a job in a single-user system, the program counter is initially set to ____.

A) the address of the last memory location
B) the number of instructions
C) zero
D) the address of the first memory location

Question 24

The fixed partition scheme works well ____.

A) when jobs have the same size
B) when jobs have different sizes
C) when job sizes are not known in advance
D) when all jobs are under 100K

Question 25

During compaction, the operating system must distinguish between addresses and data values, and the distinctions are not obvious once the program has been loaded into memory.

Question 26

Compaction should always be performed only when there are jobs waiting to get in.

Question 27

Consider the following space requirements for jobs 1-4 and memory blocks. Assuming a best-fit scheme is used, the job,____, is placed in the last block. Jobs:
J1 10K
J2 20K
J3 30K
J4 10K
Blocks:
B1 30K
B2 15K
B3 50K
B4 20K

A) J1
B) J2
C) J3
D) J4

Question 28

In the partition scheme, the table that the Memory Manager uses to keep track of jobs is composed of the ____.

A) partition size, memory address, and status
B) status, access, and memory address
C) partition size, status, and access
D) partition size, memory address, access, and status

Question 29

Assume the Memory Manager receives a request for a block of 200. When the best-fit algorithm is used, ____ is the beginning address of the block granted by the Memory Manager. Beginning Address Memory Block Size
4075 105
5225 5
6785 600
7560 20
7600 205
10250 4050
15125 230
24500 1000

A) 6785
B) 7600
C) 10250
D) 15125

Question 30

The bounds register is used to store the highest (or lowest, depending on the specific system) location in memory accessible by each program.

Question 31

Memory is allocated during garbage collection.

Question 32

The following algorithm can be described as ____. 1 Set counter to 1
2 Do while counter <= number of blocks in memory
If job_size > memory_size(counter)
Then counter = counter + 1
Else
Load job into memory_size(counter)
Adjust free/busy memory lists
Go to step 4
End do
3 Put job in waiting queue
4 Go fetch next job

A) first-fit memory allocation
B) best-fit memory allocation
C) least-fit memory allocation
D) fixed partition memory allocation

Question 33

Fixed partitions are also called ____ partitions.

A) complete
B) static
C) direct
D) sized

Question 34

Consider the following space requirements for jobs 1-4 and memory blocks. Assuming a first-fit scheme is used, the job,____, is not able to run. Jobs:
J1 10K
J2 20K
J3 30K
J4 10K
Blocks:
B1 30K
B2 15K
B3 50K
B4 20K

A) J1
B) J2
C) J3
D) J4

Question 35

____ consists of fragments of free memory between blocks of allocated memory.

A) An inefficient fit
B) Indirect partitioning
C) External fragmentation
D) Internal fragmentation

Question 36

____ has the least wasted space and the smallest partition fitting the requirements.

A) Fixed partitioning
B) First-fit memory allocation
C) Dynamic fit memory allocation
D) Best-fit memory allocation

Question 37

After relocation and compaction, both the free list and the busy list are updated.

Question 38

The ____ keeps the free/busy lists organized by memory locations, low-order memory to high-order memory.

A) fixed partition allocation
B) first-fit memory allocation
C) dynamic fit memory allocation
D) best-fit memory allocation

Question 39

____ is the first step in the algorithm to load a job in a fixed partition.

A) Comparing job size to size of largest partition
B) Determining the job's requested memory size
C) Setting counter to one
D) Placing the job in a waiting queue

Question 40

The following,____, describes the first memory allocation scheme.

A) Each program to be processed was loaded into secondary storage, then swapped into memory in parts
B) Each program to be processed was partially loaded into memory, then granted more memory as needed
C) Each program to be processed was allocated a portion of memory and could negotiate with other programs to access more memory
D) Each program to be processed was loaded in its entirety into memory and allocated as much contiguous space in memory as it needed

Question 41

The ____ of memory, sometimes referred to as garbage collection or defragmentation, is performed by the operating system to reclaim fragmented sections of the memory space.

A) deallocation
B) redirection
C) compaction
D) reallocation

Question 42

In a dynamic partition scheme, ____, is how the Memory Manager deallocates a block that is between two other free blocks?

A) The sizes of the three free partitions must be combined.
B) All three are moved individually from the busy list to the free list.
C) The block is combined with the larger of the two adjacent blocks.
D) The status of the block is set to free.

Question 43

A(n) ____ in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list.

A) blank line
B) null entry
C) joined entry
D) empty entry

Question 44

The operating system can tell the ____ of each group of digits by its location in the line and the operation code.

A) function
B) value
C) order
D) assignment

Question 45

The ____ contains the value that must be added to each address referenced in the program so it will be able to access the correct memory addresses after relocation.

A) busy list
B) compaction monitor
C) relocation register
D) bounds register

Question 46

____ is the actual memory address for a job that starts at 18K.

A) 1,800
B) 18,000
C) 18,432
D) 180,000

Question 47

When memory is deallocated, an entry can be removed from the free list by creating a(n) ____.

A) blank line
B) null entry
C) joined entry
D) empty entry

Question 48

____ is how memory is deallocated in a fixed partition scheme.

A) Memory Manager releases the block and combines it with another free block.
B) Memory Manager immediately gives memory to another program.
C) Memory Manager adds block to free list and removes it from busy list.
D) Memory Manager resets the status of the memory block where the job was stored to "free."

Question 49

One approach to performing compaction is to do it when a certain ____ of memory becomes busy.

A) byte
B) percentage
C) bit
D) area

Question 50

By compacting and relocating, the Memory Manager optimizes the use of memory and thus improves throughput, but an unfortunate side effect is more ____.

A) null entries
B) segmentation
C) errors
D) overhead