Software Development Flashcards
Coding:
how alphanumeric data and control characters are represented by sequences of bits
American Standard Code for Information Interchange (ASCII)
- 7-bit code permitting (2)^7 = 128 different combinations
- commonly used in desktop computers
Extended Binary Coded Decimal Interchange Code (EBCDIC)
- used in IBM mainframe computers
- 8-bit code permitting (2)^8 =256 different characters
program
sequence of computer instructions that perform some function
- designed to implement an algorithm
algorithm
procedure consisting of a finite set of well-defined steps
source code statements:
- instructions like READ, GOTO, OPEN
- translated into machine-readable object code to produce executable program
variable
- used by a program to store a value
- can be known or unknown
declaration
- defines a variable
- specifies the type of data a variable can contain
- reserves space for the variable in the program’s memory
assignment
give values to variable
command:
instructs the program to take specific action
function:
specific operation grouped into a unit that can be called within the program
flowchart
- step by step representation of a specific procedure or algorithm
- -> terminal: begins and ends flowchart (pill shaped)
- -> input/output: defines an i/o operation (rhombus)
- -> processing: defines a calculation or data manipulation (rectangle)
- -> predefined process (subroutine): refers to a calculation or data manipulation formally defined elsewhere (square with stripes on left and right sides)
- -> decision: indicates a branch or question in the process flow (typically two options, such as yes and no) (diamond)
- -> connector: indicates flowchart continues elsewhere (circle)
- -> off-page: indicates flowchart continues on following page (looks like home base plate)
- -> annotation: indicates a comment (rectangle with dotted line)
machine language instructions:
- compatible with and readily understood by the central processing unit (CPU)
- each instruction must be expressed as a series of bits (intrinsic machine code)
- may be written in octal or hexadecimal for convenience, then converted to binary
- instructions consists of op-codes and operands
- -> op code : operation to be performed
- -> operand: storage location
assembly language
- next-higher -level language above machine language
- mnemonic codes specify operations
- operands referred to by variable name rather than address
macros
- blocks of code repeated verbatim at multiple locations in a program
- written once and the referred to by a symbolic name
assembler
- translates assembly language into machine language
linker
- combines portions of other programs or function libraries after assembly
loader
places the program in the computer’s memory in order to run it
A portion of computer code contains the instructions LR, SC and JL. Most likely these are A) machine language B) assembly language C) object code D) interpreted code
B) assembly language
–> assembly language usually consists of short commands such as LR for loading a value into the register, SC for storing a result in location C, and JL for jumping if the result is less than a given number. Assembly language is translated into binary machine language (also known as “object code”) by an interpreter or compiler program
relative computational speed languages
slower faster
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interpreted program pseudo-compiled compiled assembly language
structure:
in a structural language, each subroutine and other procedure has one specific entry point and one specific return point.
strong data typing
- different types of data are defined and cannot be interchanged
- for example, integers and real number cannot be combined in arithmetic statements
weak data typing
- data of one type can be used where data of another type is expected
- for example, the number 3 can be added to the alphanumerical string “4” to get 7. (in a strongly typed language, this would probably result in an error.)
portability
a portable language can be implemented on different machines