Operating system development history
The operating system was not born with computer hardware, it was in the process of people using computers, in order to meet two major needs: improve resource utilization, enhance computer system performance, with the increasing development of computer technology itself and its applications, and gradually formed and perfected.
binary
Encoding
ASSIC Each character needs 8 bits to store the
computer capacity
1 bit = 1bit
8bit = 1byte = 1 byte
1024bytes = 1kbytes = 1KB 1024 characters, small documents, hundreds of k can represent a picture
1024KB = 1Million Bytes = 1MB = 1 megabyte, tens of thousands of words of document, large picture
1024MB = 1Gigabytes, a clear movie, not high-definition, high-definition can reach several 10 g
1024GB = 1TB,
1024TB = 1PB,
00000000
00110001
00000001
Introduction to Programming Languages
What is a programming language?
Define a set of grammatical rules for interacting with the computer, and this set of rules can be called a programming language.
We do not understand Japanese because we do not understand the grammatical rules
Learning programming == learning grammar rules
What can programming do?
print hello world
eject cd
a combination of a bunch of instructions == 》 Software
There are
more than 600 programming languages
C = development language for various operating systems 1973
C++ = C++ is an enhanced version of C language, 1983 , Bjarne Stroustrup of Bell Labs introduced C++[1] on the basis of C language. C++ further expands and perfects the C language and is an object-oriented programming language.
java = 1995 developed by sun company, java virtual machine supports cross-platform
php = 1994, pure web development language, 1994 Netscape browser was born
python = born in 1989, it was just used as a scripting language, developing small tasks, with linux Born in the same year, 89, 1991, the collapse of the Soviet Union, the official version in 1991
C# = c sharpe = C# is an object-oriented high-level programming language released by Microsoft and running on the .NET Framework. And is scheduled to appear on stage at the Microsoft Professional Developers Forum (PDC). C# is the latest work of Microsoft researcher Anders Hejlsberg. C# looks strikingly similar to Java; it includes things like single inheritance, interfaces, almost the same syntax as Java, and the process of compiling into intermediate code and then running it. But C# is obviously different from Java. It draws on a feature of Delphi, it is directly integrated with COM (Component Object Model), and it is the protagonist of Microsoft's .NET windows network framework.
ruby =
Ruby, a simple and fast object-oriented (object-oriented programming) scripting language, developed by Japanese Yukihiro Matsumoto in the 1990s, under the GPL agreement and Ruby License. Its inspiration and features come from Perl, Smalltalk, Eiffel, Ada and Lisp languages. Ruby language alternatives for other platforms such as JRuby (Java platform) and IronRuby (.NET platform) have also been developed from the Ruby language itself. The author of Ruby started writing Ruby on February 24, 1993, and it was not officially published on fj (newsgroup) until December 1995. Because Perl is pronounced the same as the June birthstone pearl (pearl), Ruby is named after the July birthstone ruby (ruby).
Ruby on rails web framework
perl = language developed on Unix platform, very powerful for word processing, can write code that no one can understand
Shell = scripting language, easy to learn, based on unix, linux, do some simple system management Task, operation and maintenance personnel must learn
scalar = Scala is a multi-paradigm programming language, a programming language similar to java [1], big data development
erlang = is a general-purpose concurrency-oriented programming language developed by the Swedish telecom equipment manufacturer Ericsson, functional programming
go === Go language is the second open source programming language released by Google in 2009. The Go language is optimized for programming of multiprocessor system applications. Programs compiled with Go can be as fast as C or C++ code, and are more secure and support parallel processes.
javascript = is the most widely used language at the moment, mainly writing front-end language,
nodejs = back-end full-stack language
vb = Microsoft scripting language, bat script
lua = nginx scripting language, ngnix is the most nb web server nowadays