Understanding Software Systems and Programming Concepts
What Are Software Systems?
Software systems consist of software used to manipulate and interact with the system, providing control over the hardware and supporting other programs.
Core Computer Components
- Memory: Consisted of 4096 words, each 40 bits. Every word could contain two instructions of 20 bits each or a whole number of 39 bits and its sign.
- Control Unit: Determines the next instruction to execute and passes it to the ALU.
- Arithmetic Logic Unit (ALU): Responsible for performing arithmetic and logic operations necessary for the execution of an instruction.
- Input: Any device through which information is entered into the computer.
- Output: Any device that receives information from the machine to be used by the user.
Problem Solving Approach
- Defining the problem
- Problem analysis
- Selecting the best alternative
- Diagramming
- Writing Test / Testing
- Consolidation
- Transcription / Documentation
- Compilation
- Computer tests / Execution
- External documentation
Software Editors
- Nature Publishing Editor: A program that allows modifying predefined characters or creating custom ones.
- Text Editors: A text editor is a program that lets you create and edit digital files containing only plain text, commonly known as text files or plaintext.
- Online Editors: The line editor is used to create or edit the Definition Table Fields and Field Selection Table. These tables are formed by one or more lines, each representing a descriptive element.
- Screen Editors: An editor that works line by line and displays a screen of text at once.
Programming Languages
A programming language is a set of symbols and syntactic and semantic rules that define its structure and the meaning of its elements and expressions. It is used to control the physical and logical behavior of a machine.
Language Levels
- High-level language: Achieves independence from a specific machine and approaches natural language (e.g., C, Java, Fortran, Basic).
- Mid-level language: These languages are at a midpoint between high and low levels. C could be considered mid-level because it can access system registers and work with memory addresses (characteristics of low-level languages) while also supporting high-level operations.
- Low-level language: Languages totally dependent on the machine, meaning a program written in such a language cannot be easily migrated or used on other machines. They are practically tailor-made for the hardware, making the most of its characteristics.
Language Generations
- First generation: Machine language.
- Second generation: Created the first assembly languages.
- Third generation: Established the first high-level languages (e.g., C, Pascal, COBOL).
- Fourth generation: Languages capable of generating code by themselves, often called RAD (Rapid Application Development) tools, allowing application creation without deep language expertise. Object-oriented languages also belong here, enabling code reuse (e.g., Visual Basic, Natural Adabas).
- Fifth generation: Languages oriented towards artificial intelligence. These languages are still under development (e.g., LISP).
Translators, Compilers, and Interpreters
A translator is any program that takes text written in a source language as input and produces text in an object language as output.
A program compiled by a compiler can run by itself because the compilation process transforms it into another language (typically machine language). A compiled file can be easily distributed for a specific platform.
An interpreter translates the program line by line as it executes, directly converting the code into actions. An interpreted program requires the interpreter to run. The advantage is that an interpreted program can run on any platform that has the interpreter installed. However, a compiled file only works on the platform where it was created.
Regarding execution speed, a compiled file is typically 10 to 20 times faster than an interpreted file.