4.3 - Programming Language Classification Flashcards
What was the colossus?
Developed by Tommy Flowers and built at Bletchley Park in 1943
What was the input and output of the colossus? How was it programmed?
Input was a continuous loop of paper tape with 20,000 5-but characters
Output was an indicator lamp panel
Programmed using switches and plug panels
What were the computers in the late 1940’s like?
Limited memory with each memory cell consisting of a vacuum tube the size of a light bulb
Programmed using machine code, entered using a series of switches
What is operation code?
Part of a machine code instruction that defines the operation to be performed
What is an operand?
The quantity on which an operation is to be done
Where is the opcode and operand held in machine code?
Opcode in the first few bits
Operand in the rest of the bits
What is an instruction set?
All the introductions that the computer can understand and execute
How was assembly language an improvement of machine code?
Each opcode was replaced by a mnemonic which gave a clue as to what the operation did
The operand was replaced by a decimal (or hexadecimal) number
What is an advantage of assembly code over machine code?
- easier to write
- easier to understand
- easier to debug problems
What is the disadvantage of assembly code?
Code has to be translated into machine code by an assembler
What is an imperative high-level language?
Consists of commands for the computer to perform
What are declarative languages?
Focuses on what the program Gould do without listing the steps needed to achieve the result
Opposite of imperative high-level language
E.g. SQL
Why are high level codes better for coders?
Programmer can think and code in terms of algorithms rather than worrying about how the computer will execute each tiny step
How are high level programs converted into machine code?
Using an assembler or compiler to turn into object code
What is the relationship between assembly language and machine code?
1 to 1 relationship
