Key Concepts in Operating Systems: Memory, Processes, and Programs
Dynamic Partitioning: An Example
A hole of 64K is left after loading 3 processes: not enough room for another process.
Eventually, each process is blocked. The OS swaps out process 2 to bring in process 4.
Another hole of 96K is created.
Eventually, each process is blocked. The OS swaps out process 1 to bring in process 2 again, and another hole of 96K is created…
Compaction would produce a single hole of 256K.
Difference Between Fixed and Dynamic Partitioning
Fixed Partitioning
- Partitions main memory
Database Objectives and Architecture: A Comprehensive Look
Objectives of a Database
- Data Independence: Ensuring independence between data and the applications that use them. This includes:
- Physical Independence: The ability to modify the physical schema without affecting the higher levels.
- Logical Independence: Changes to the conceptual schema do not necessitate modifications to application programs.
- Minimal Data Redundancy: Minimizing unnecessarily repeated data to avoid inconsistencies. Providing mechanisms to monitor operations on the database.
- Versatility
Understanding Access Control in C++ Inheritance
Protected Members
A protected member is inaccessible to all clients at all levels. If a protected data member is inherited, it is not accessible to the clients of this derived class, no matter what the access control is.
Protected items are things you need to write your functions, but you do not want any client to know about. For example, ListError.
Example
class base
- private a // base’s client cannot use; cannot be passed down either
- protected b // base’s client cannot use; can be passed down
- public c
QBA 1720 Exam 2: Key Concepts & Excel Functions
QBA 1720 Exam 2 Note Sheet
Key Concepts and Formulas
Measures of Central Tendency:
Mean (Average):
=AVERAGE(range)Median:
=MEDIAN(range)Mode:
=MODE.SNGL(range)
Measures of Variability:
Standard Deviation:
=STDEV.S(range)Variance:
=VAR.S(range)68-95 Rule:
68% of data is within 1 standard deviation.
95% of data is within 2 standard deviations.
COUNTIFS Function:
Counts based on multiple conditions:
=COUNTIFS(criteria_range1,criteria1,[criteria_range2,criteria2],…)Example: Count the number of students who
Public and Private Keys: Understanding Encryption and Security
Public and Private Keys: Understanding Encryption
Public Key
The encryption key is shared publicly with many people. However, only the person or company that created the key can decrypt the information.
Private Key
The creator is the only one who knows how to encode and decode. They can only read or hide the information from those to whom they provide instructions.
Symmetric and Asymmetric Encryption: Main Problems
Symmetric Encryption
- Requires a secure channel for key exchange.
- Does not guarantee authenticity
Understanding Operating Systems: Functions and Usage
An operating system is a program or set of programs that allows you to manage the resources of a computer. It starts working when you turn on the computer, enabling user interaction. The operating system manages the installation, configuration, usage, and maintenance of software and computer hardware. There are two main types:
- Windows: A commercial operating system owned by Microsoft. They have developed a family of operating systems that have evolved over time.
- Linux: A free and open-source operating