There exists 5 different types of operating systems that are distinguished from one another by the response time and how the data is entered in the system. These types are interactive, batch, real-time and embedded systems. Below are the fundamental differences between each:
Introduced in first generation computers.
Relied on stacks of punched cards and magnetic tapes for input.
Batch system performance was measured in the throughput which are the number of jobs completed an hour.
Introduced to address the demand of faster turnaround compared to the efficiency of batch systems and for debugging programs
Slower than real time systems
Time sharing software was introduced so users can interact with their computer system via type writer programs like terminal and command prompt on windows.
Real Time Systems
Used in time-critical environment such as space flights, airport traffic control, high-speed aircraft where reliability is important and data is processed within a time limit. Must be 100% responsive at all times
Two types of real systems (hard and soft)
Time limit needs to meet the deadline but doesn’t need to be ultra-fast.
Defined as computers integrated in diverse products to add features and capabilities. Examples of such are household appliances, cars, digital music players and elevators.
Takes advantage of the computers limited resources by having each system perform a specific set of programs.
They aren’t interchangeable among systems.
Chapter 2 Exercise 2
Internal Fragmentation, the job list table pushes the data to the memory list table which gets compacted into different categories including memory location, memory block size, job number, job size, status and internal fragmentation.
Chapter 2 Exercise 5
Fixed Partition: commercially available in 1950’s to 1960’s main memory is partitioned permits multiprogramming partition sizes remain static disadvantages (requires contiguous loading of the entire program, job allocated method, arbitrary partition leads to undesired results)
Dynamic Partition: main memory is partitioned job allocated method disadvantages (full memory utilization only during loading of first jobs, subsequent allocation, memory waste)
Chapter 2 Exercise 7
Part A – Best Fit
|Job 1 |690 k |Block 1 |900k (low order memory) |
|Job 2 |275 k |Block 3 |300k (high-order memory) |
|Job 3 |760 k |Block 2 |910k |
Part B – First Fit
|Job 1 |690 k |Block 1 |900 k |
|Job 2 |275 k |Block 2 |910 k |
|Job 3 |760 k |……. |……. |
Chapter 2 Exercise 8
Part A – Best Fit
|Job 1 |275 k |Block 3 | 300 k |
|Job 2 |920 k |…. |…. |
|Job 3 |690 k