Exam 2: Memory Management: Early Systems

A single-user system supports multiprogramming.

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.

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).

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

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.

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

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

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

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

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

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.

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

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.

Fixed partitions are also called ____ partitions.

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

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

The first attempt to allow for multiprogramming used fixed partitions.

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

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

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