Lecture 1 - Intro To Systems Programming

Question 1

What is systems proramming?

Answer 1

Activity of writing computer system software that will be used as a platform for other software. i.e. there is a layer of abstraction

Question 2

Examples of system software…

Answer 2

Drivers , OS , compilers

Question 3

What is the software that is contrasted with system software?

Answer 3

Application software

Question 4

What are the performance constraints usually imposed on system software?

Answer 4

• fast execution time
• low memory consumption
• low energy usage

Question 5

What do systems programming languages provide?

Answer 5

More fine grained control over the execution of programs

Question 6

What are the two examples of system programming languages?

Answer 6

C and C++

Question 7

What are the 4 programmig paradigms?

Answer 7

imperative
structured
object-oriented
functional

Question 8

What is imperative programming?

Answer 8

Computations are sequences of statements that change program state

Question 9

What is structred programming?

Answer 9

Structured programming organises programs with subroutines and structured control
flow constructs

Question 10

What is object-oriented programming?

Answer 10

Object-oriented programming organises programs into objects that contain data and
encapsulate behaviou

Question 11

What is functional programming?

Answer 11

In functional programming programs are mathematical functions and avoid explicit
change of state

Question 12

What is the Python statement that gets the size of variable in memory?

Answer 12

sys.getsizeof(variable)

Question 13

What is the C statement that gets the size of a variable in memory?

Answer 13

sizeof(variable)

Question 14

Why should we use C for systems programming?

Answer 14

Has a high level of control, which allows strong reasoning about the program’s performance and execution behaviour

• we can be more confident about the program overhead

Question 15

What must we do to a C program to execute it?

Answer 15

Compile it

Question 16

What does the compiler do?

Answer 16

Translates source code to machine code via a number of steps.

Question 17

How to compile a C program using clang?

Answer 17

clang source.c -o name

Question 18

What happens when attempting to compile?

Answer 18

1. Preprocessor expands macros
2. Source code is parsed and turned into intermediate code
   3.machine-specific assembly code is generated
   4.machinecode is generated in an object file
   5.The linker combines multiple object files into an executable, if required

Question 19

How to generate the result of the preprocessor stage?

Answer 19

clang source.c -E -o name.e

Question 20

How to generate the result of the intermediate representation stage?

Answer 20

clang source.c -emit-llvm -S -o source.llvm

Question 21

How to generate the assembly code?

Answer 21

clang source.c -S -o source.s

Question 22

How to generate the machine code?

Answer 22

clang source.c -c -o source.o

Question 23

What does the linker do?

Answer 23

Linker combines one or more object files into a single executable. It does so by checking if all functions have machine code available, if not and it cannot be found it throws up an error.