CPU Scheduling Algorithms and Inter-Process Communication
CPU Scheduling Algorithms
1. Determining Length of Next CPU Burst
Estimating the length of the next CPU burst can be done using exponential averaging or the length of previous CPU bursts.
2. Priority Scheduling
Each process is assigned a priority number, with the highest priority (smallest integer) being allocated the CPU. Shortest Job First (SJF) is a priority scheduling algorithm where priority is based on the predicted next CPU burst time. However, this algorithm can lead to starvation, where low-
Read MoreDesign Patterns and Principles
Designing
A creative process where the designer has a goal given by the customer, no construction work or algorithm. Object oriented way of dividing a complex whole into independent, co-operating components. The challenge is to find a natural division. System is a task automatized by software. The scope is normally defined by the customer.
Agile
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding
Number Systems, Data Representation, and Compression
Number Systems
Hexadecimal
There is no single symbol (digit) to represent 16 in hexadecimal. The hexadecimal number 10 corresponds to the decimal value 16.
Binary
The devices used to store and manage data on a computer are cheaper and more reliable if they only have to represent two possible states. Every electrical signal is considered to be either “low” or “high” that map to the binary digits 0 and 1.
There are 2 digits in the binary number system.
Decimal
There are 10 digits in the decimal number system.
Read MoreTelecommunications Networks: ISDN, ATM, Transmission Media, and Digital Switching Systems
ISDN Networks
– Duplex Transmission of Signal (Echo Cancellation), Principle of Scrambler
– DEC (Digital Echo Cancellation): Simultaneous transmission in both directions by additive block, it adds incoming useful signal, parasitic reflected signal and compensation signal produced by transversal filter, which its adaptive regulated by control processor.
– Transmission of periodic sequences can negative affect function of echo compensator, so we have to use methods of signals scrambling:
- Recovering of
Digitalization and Multiplexing Techniques in Telecommunications
1. Digitalization of Telephone Channel, Quantization Distortion (Noise)
Telephone channel, unidirectional path from 300 to 3400 BW:3100Hz. Its digitalization with PCM(pulse code mod), if adds TDM(time div mult), it increments the efficiency utilization of the transmission paths. PCM converts analogue samples to digital forms (increments noise immunity transm). 3 ops(A/D converter) to analogue signal before mult & transm: 1-Sampling(signal discrete in time, Fsampling=1/Ts, sampling theorem Fmax
Read MoreNetwork Protocols: A Comprehensive Guide to ICMP, UDP, TCP, Routing, and Address Translation
ICMP (Internet Control Message Protocol)
ICMP is responsible for reporting protocol, IP level, in different situations, such as errors, unreachable routes, problems, etc.
Each ICMP message contains a Message Type field, type code, checksum, IP header that caused the error, and special information by type of message.
Use:
- Ping: to check the IP level connectivity between two hosts, ensuring that it works with the software and the network path is correct. In his field data include an identifier and a sequence