1.2.2 Applications Generation

Question 1

What are the 2 main types of software?

Answer 1

• Applications software performs a specific task for the user, running on systems software. (Ex. word processing, browsers).
• Systems software is low-level software that runs the device smoothly. No direct user interaction. (Ex. OS, utilities, drivers).

Question 2

What are the main examples of utility software?

Answer 2

• Compression shrinks file sizes for internet transfer and storage saving.
• Disk Defragmentation rearranges the programs in storage into contiguous physical order to improve performance.
• Antivirus checks downloads and programs for malware signatures.
• Automatic updating and backups ensure all software runs the latest version and all data is backed up for recovery.

Question 3

What is open-source software?

Answer 3

• Source code that can be used, modified and distributed by anyone.
• Allows community technical support and modification to fit needs, but developer support may be lacking, and of lower security standards.

Question 4

What is closed-source software?

Answer 4

• Proprietary software with a hidden source code, requiring a (usually paid) license to use.
• Thoroughly tested and with high levels of support and security.
• Can be expensive and is unmodifiable.

Question 5

What are the 3 types of translators?

Answer 5

• Compilers turn high-level code into machine code in one go, while carrying out checks and forming an error report. Slowest translation, fastest code. Also produces intermediate code.
• Interpreters translate high-level code line by line, stopping at any errors. Useful for testing but slower than compiled code.
• Assemblers translate assembly code into machine code on a 1:1 basis. Assembly code is platform specific.

Question 6

What are the stages of compilation?

Answer 6

• Lexical analysis removes comments and whitespace, then replaces codes with tokens and a symbol table.
• Syntax analysis checks the tokens against the rules of the programming language. Produces an abstract syntax tree.
• Code Generation uses the syntax tree to produce machine code.
• Optimisation involves searching through code and replacing parts of it with identically functioning, more efficient code, and removing redundant parts.

Question 7

What are linkers, loaders and libraries?

Answer 7

• Linkers can be static or dynamic. Static linkers add modules directly to the file. Dynamic linkers include the addresses of modules, keeping files smaller.
• Loaders retrieve a library or subroutine when executing a file.
• Libraries are pre-compiled, free-to-use tested code that programmers can make use of to save time.