Week 7

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AnnouncementsBasic and Advanced 4 due October 18

Basic, Advanced 5 due October 22

Basic, Advanced 6 due October 27

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Lecture 7: Potpourri

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OverviewHow do computers understand us?

Fields and jobs in EECSInternships

GNU/Linux experience

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How do computers understandus?

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Quick rundown on comp archParts

CPUThe star of the show: handles general workloads

Memory (RAM)

Storage (HDD, SSD)

AcceleratorsGPU

MotherboardConnects everything together

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How do computers work?The CPU executes a sequence of instructions in the form of binary

This is known as machine code

The instruction set architecture defines what instructions there are and how they areencoded in binary

Yes, even CPUs have their own languages

Example ISAs: x86-64, ARMv8, RISC-V, MIPS

CPUs perform relatively rudimentary operationsArithmetic: add, sub, mul, div

Control: br, jmp

Memory: ld, st

(These are generic instruction names)

Example operation: "add 5 to variable"x86-64: [0x48,0x83,0xc0,0x05]

AArch64 (ARMv8): 0xe2800005

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How do computers understand us?Writing a program in machine code with a hex editor is not most people's idea of fun

Assembly languages are human readable representations of machine instructionsx86-64: add rax, #5 -> [0x48,0x83,0xc0,0x05]

AArch64 (ARMv8): add r0, r0, #5 -> 0xe2800005

An assembler takes assembly code and turns it into machine code

Assembly is still rather cumbersome to useYou're still working with machine instructions

You just now you have a tool that remembers how instructions are encoded

This isn't portable: assembly for one ISA won't work for another

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How do computers understand us?Higher level languages were developed

Raises abstraction level: can think in arithmetic expressions and higher levelconstructs

Leads to portability since you don't have to worry as much about hardware/ISAs

"Classic" classesCompiled

Interpreted

Things get a bit hazyByte-code

Just-in-time (JIT) compilation

Keep in mind languages don't necessarily need to fit any one classification

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Compiled languages"Compilation" in general refers to taking the language and producing a lower levelform

Compiled languages usually have the source code compiled down to the machinecode level

The CPU can directly run this machine codeThis is fast

Examples: C, C++, Fortran, Go, Objective-C, Rust, (Java*)

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Interpreted languagesThese languages usually are read by another program known as an interpreter

This program will parse statements and do something based o� of them

This is understandably slow and there are other strategies to improveperformance

Examples: Shell, Bash, Python, Ruby

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Lines get hazySome languages compile down to byte-code that is meant to be e�iciently interpreted

Java is a poster child

Some languages have interpreters that do just-in-time (JIT) compilationSource code is compiled to machine code at runtime

Traditional compilation is known as ahead-of-time (AOT) compilation in contrast

Ultimately these aren't really hard classificationsYou can compile Python if you want

You can write a C interpreter if you

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Running a programOn *nix systems you can execute both machine code and interpreted programs

Machine code programs are put into file formatted with data pertaining toexecution known as an "executable"

The execute permission bit must be set for you to execute a program file

Executable file formats have information that can identify their file type

*nix systems will recognize the shebang (#!) on the first line to figure that it's aninterpreted program, then call the appropriate interpreter

If there's no shebang, the OS will generally assume it's a shell script

#!/bin/env python3: invoke the /bin/env executable to find thepython3 executable

#!/bin/bash: invoke Bash as the interpreter

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Questions?

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Fields and jobs in EECS

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EECS is a very broad subjectNo wonder when you have EE, CE, and CS all in one acronym

There's a lot of di�erent ways to divy up the space: this is just my conception of it

I'll keep it computer-relatedSorry, analog and power EEs

Not an all-encompassing list

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DomainsComputer hardware

Physical design engineer

RTL/ASIC design engineer

Design verification engineer

Computer architect

Hardware-so�ware twilight zoneEmbedded systems engineer

Firmware engineer

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DomainsComputer systems

Systems so�ware engineer

Compiler engineer

Embedded so�ware engineer

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DomainsApplications

Desktop so�ware developer 🦕

Mobile app developer 📱

Front-end web developer

Back-end web developer

Full-stack developer

So�ware engineer*

DevOps engineer

Testing/QA engineer

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DomainsData science

Data analyst

Data engineer

Machine learning engineer

Other areasCybersecurity

Robotics

Scientific computing/simulation

Research

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IndustriesYou can find these jobs in various industries

Tech

Gaming

Finance

Telecommunications

Defense

Government

Health care

and more (you'd be surprised at the opportunities in the restaurant industry)

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InternshipsGreat way to get experience and build up your resume

I learned a lot of my practical skills on the job

Job postings will go up during the Fall and early Winter: try to nab them!That doesn't mean all hope is lost if you're applying in late February/March

I got my internships as a "late" applicant

It doesn't cost anything to apply, unlike with college applications

Career fairs are not the only way to applyYou can still find success in online applications

Interviews o�en have a behavioral and technical portionBehavioral interview will involve questions about you as a person

Technical interview will test your knowledge

Getting an answer wrong on a technical interview isn't the end of the world: o�enthe interviewer is just as interested in your problem-solving process

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InternshipsIf your summer is open, try looking for an internship!

If you have companies in mind, check the job postings on their website

You can use websites like Indeed, Glassdoor, and LinkedIn to browse for jobs and seewhat's around

You might find something you like based on the description!

r/cscareerquestions can be a useful place to get some opinions on how the job marketis doing

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Questions?

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GNU/Linux experience

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GNU/Linux experienceGNU/Linux o�ers a very large degree of freedom in setting up your system

You are in control of your computer

Lots of free alternatives to commonly used so�wareO�ice applications: LibreO�ice

Note taking: xournal++

Video editing: Kdenlive

Photo processing: darktable

Art: Krita, Inkscape

Fun list (it's for Arch, but gives a sense of what's there)

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Building your own environmentA Linux distribution encompasses a so�ware collection, the Linux kernel, and aparticular philosophy

Many distributions come with a lot of stu� and a particular look a feel, but you still havethe ability to radically change how they look and operate

What's most evident is the graphical user interface (GUI); here's some vocab

Display server: so�ware that handles the graphics for various client applicationse.g. X11, Wayland

Window manager: so�ware that manages control and appearance of windowse.g. awesome, i3, xmonad

File manager: so�ware that presents an interface for managing filese.g. Nautilus, Dolphin

Desktop environment: an all-in-one integrated environment that presents a fulldesktop experience, integrating a window manager, toolbars, file manager, networkmanagement, web browsing, etc.

e.g. GNOME, KDE Plasma, Xfce, LXQt

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Putting it together from the ground upI'll be using virtual machines to illustrate the OS installation process

Virtual machines (in this context) are emulated computer systemsYou have virtual CPUs and virtual storage and virtual monitors for your virtualmachine

You can install operating systems on them and treat them like any other computer

Fun fact: the course server is running on a virtual machine

I'll first install Ubuntu Linux on a VM to illustrate the typical Linux installation process

I'll then install Arch Linux on a VM to illustrate putting together a personalized setuppiece by piece

It's relatively quick to install since it doesn't install much in the beginning

While I stan Arch, there's nothing wrong about other distros

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Putting it together from the ground upInstallation media

Setting up a VirtualBox VM

OS installationUbuntu

Arch

OS setup and customization

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Questions?

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