Chapter 1 - Part 1

Question 1

What does the preprocessor do in C and what does it output?

Answer 1

The preprocessor modifies the original C program and outputs ASCII text.

Question 2

What does the assembler stage do in a C program, and what does it output.

Answer 2

The assembler stage translates the assembly code into machine language instructions. It is output in a binary format, called a relocatable object program.

Question 3

What does the compilation stage do in a C program, and what format does it output?

Answer 3

The compilation stage converts the C code into assembly language and outputs the generated code as text (usually with a .s extension).

Question 4

What does the linking stage do in a C program?

Answer 4

Linking merges other object files referenced by the C program, and outputs an executable file (in machine language binary), which is ready to be loaded into memory.

Question 5

How do you convert hex to binary using the bc command line tool?

Answer 5

echo ‘obase=2;ibase=16; A’ | bc

Question 6

First stage of C compilation + clang command

Answer 6

Preprocesser: clang -E hello.c > hello.i

Question 7

Second stage of C compilation + clang command

Answer 7

Compiler: clang -S hello.c

$ hello.s

Question 8

Third stage of C compilation + clang command

Answer 8

Assembler: clang -c hello.c

$ hello.o

Question 9

Fourth stage of C compilation + clang command

Answer 9

Linker: clang hello.c

$ a.out

Question 10

How large is a word?

Answer 10

Words refer to a fixed size of bytes, but have no fixed size. Most modern machines use either 4 bytes (32 bits) or 8 bytes (64 bits).

Question 11

Name 4 standard I/O devices.

Answer 11

Keyboard, mouse, display, disk.

Question 12

For I/O devices, what’s the difference between a controller and an adapter.

Answer 12

A controller is soldered into the motherboard, an adapter plugs into motherboard slot.

Question 13

What does DRAM stand for?

Answer 13

Dynamic random access memory.

Question 14

What is a word-sized storage device in the CPU called?

Answer 14

register

Question 15

What is the program counter in a CPU.

Answer 15

The program counter contains the address of a register holding the next machine language instruction it will execute.

Question 16

What does ALU stand for in a processor?

Answer 16

arithmetic logic unit

Question 17

What is a ‘register file’?

Answer 17

A register file is a storage device that consists of multiple registers with unique names.

Question 18

What does the ‘load’ machine operation do?

Answer 18

Copies data from main memory and stores it in a register, overwriting whatever was previously there.

Question 19

What does an ‘operate’ operation do?

Answer 19

Copies the contents of two registers to the ALU, performs an arithmetic operation on the two registers, and stores the result in a new register, overwriting what was there.

Question 20

What does a ‘store’ operation do.

Answer 20

Copies a word from a register to the main memory, overwriting what was there.

Question 21

What does a ‘jump’ operation do?

Answer 21

Gets a word from the instruction, and copies it to the program counter.

Question 22

What’s the difference between a machines instruction set architecture and its microarchitecture?

Answer 22

The ISA is an abstraction over the microarchitecture. The ISA describes what each instruction will do, and the microarchitecture handles the actual implementation.

Question 23

Approximately how much faster can a processor read code from a registry file than main memory?

Answer 23

~ 100x

Question 24

What does SRAM stand for, and what is it used for on the hardware level?

Answer 24

Static random access memory. It is used to create caches that are smaller than the main memory, but faster and closer to the CPU. These are usually called L1, L2, and L3 caches, and their sizes get larger as the go up in levels.

Question 25

What does the term locality mean with respect to memory

Answer 25

Locality refers to the tendency for programs to access data and code in localized regions.