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A10.1 Classifying software

Operating systems, software and translators · A level · OCR H446 1.2.2, AQA 7517 4.6.1.2, Eduqas A500QS 2.7 · about 30 min

BugBotLab

What this lesson is about

System and application software, utilities, libraries and translators, and open versus closed source.

Questions 5 marks in all

  1. [1 mark]Which of these are system software?

    Tick every answer that is true.

    1. AA compiler
    2. BA disk defragmenter
    3. CA maths library
    4. DA spreadsheet package
    5. EA payroll program
    Answer: A, B, C. Translators, utilities and libraries all exist to run or support the computer and other programs; a spreadsheet and payroll do a job for the user.

  2. [1 mark]What is a library?

    1. AA collection of pre-written, tested routines that other programs can call
    2. BA program that translates source code into machine code
    3. CA folder where the operating system keeps its files
    4. DAn application for searching documents
    Answer: A. A library has no main program of its own; programs link to its subroutines.

  3. [1 mark]A small charity needs software to record donations. Which is the strongest reason to choose off-the-shelf software over bespoke?

    1. AIt is available now, costs less, and has been tested by many users
    2. BIt will match the charity's exact needs
    3. CThe charity will own the source code
    4. DIt never needs updates
    Answer: A. Bespoke software fits exactly and is owned by the client, but it is expensive and slow to produce; a small charity benefits from low cost and immediate availability.

  4. [1 mark]What makes software open source?

    1. AIts source code is available, under a licence that lets people study, change and share it
    2. BIt is free to download
    3. CIt was written by volunteers
    4. DIt has no licence at all
    Answer: A. Free of charge is not the same thing: closed source software can be free, and open source software is still licensed.

  5. [1 mark]Which is a disadvantage of closed source software for the organisation that buys it?

    1. AOnly the owner can find and fix flaws or add features
    2. BAttackers can read its source code
    3. CThere is never any official support
    4. DIt cannot be sold
    Answer: A. The buyer cannot change the code, so it depends on the company for fixes and changes.

The task: the software audit

Audit the software on a robot and the laptop that programs it. software is a list of tuples (name, kind, licence): name and kind are strings, and licence is "open" or "closed". kind is one of "operating system", "device driver", "translator", "utility", "library" or "application". Write classify(kind), which returns the string "system" for the five kinds of system software and "application" for applications. Then, for each item in order, print <name>: <group>, <licence> source, for example FreeRTOS: system, open source. After the list, print three totals, one per line: system: <n>, application: <n> and open source: <n>. Count them in your loop rather than typing them. The robot stays still.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

software = [
    ("FreeRTOS", "operating system", "open"),
    ("motor driver", "device driver", "open"),
    ("pocketpy", "translator", "open"),
    ("backup tool", "utility", "closed"),
    ("lesson browser", "application", "closed"),
    ("maths library", "library", "open"),
    ("spreadsheet", "application", "closed"),
    ("disk defragmenter", "utility", "closed"),
]

def classify(kind):
    pass

The hint students can ask for: Decide which kinds of software exist to run and look after the computer, and which exist to do a job for the user. Keep running counts in the same loop that prints each line, and print the totals after the loop.

A solution

from bugbot import *
connect()

software = [
    ("FreeRTOS", "operating system", "open"),
    ("motor driver", "device driver", "open"),
    ("pocketpy", "translator", "open"),
    ("backup tool", "utility", "closed"),
    ("lesson browser", "application", "closed"),
    ("maths library", "library", "open"),
    ("spreadsheet", "application", "closed"),
    ("disk defragmenter", "utility", "closed"),
]

SYSTEM_KINDS = ["operating system", "device driver", "translator", "utility", "library"]

def classify(kind):
    if kind in SYSTEM_KINDS:
        return "system"
    return "application"

counts = {"system": 0, "application": 0}
open_count = 0
for name, kind, licence in software:
    group = classify(kind)
    counts[group] = counts[group] + 1
    if licence == "open":
        open_count = open_count + 1
    print(f"{name}: {group}, {licence} source")
print("system:", counts["system"])
print("application:", counts["application"])
print("open source:", open_count)

Any program that meets the task's checks is marked correct in the simulator; this is one way, not the only way.