CoderDojo Loughton

Assembly Language Learning Resources

2022-11-30T09:00:00+00:00

Why learn assembly language, considering it is hardly used today?

A basic knowledge of assembly language is required to understand how CPUs work and is considered an essential part of a computer science education. Furthermore, many people consider it fun!

Which assembly language to learn

Modern Intel assembly language is designed to be written by compilers and so is quite difficult to learn for humans. There’s also not much you can practically do with it outside of writing advanced vectorised video codecs.

I recommend 6502 assembly because it is pleasant to write and it does have the practical use of creating games for 8 bit computers (for which it is still used, because those systems can’t be programmed in higher level languages optimally.) It’s also still used in embedded systems.

The Z80 is similar but I don’t like it so much.

The only other option I would consider is ARM assembly. It too was designed for humans to write, and it has the advantage of running on modern systems like Raspberry Pi. However the other aspects of these ARM systems are more complex and they don’t have the wealth of learning communities that the old 6502 systems do.

Approach

6502 assembly is not particularly difficult in itself, but a 6502 chip alone is unable to generate sound and video, so each 6502 computer required additional chips and the details of how to access them vary a lot between different systems. So I would break down learning into two (interleaved) phases:

Learn generic 6502 code. Platform doesn’t really matter. Write simple algorithms. Use a debugger to view the results in memory. Possibly use some platform specific code to output results as text.
Choose a specific platform and learn how the video chip works on that platform in order to create graphical programs and games. I think the most interesting platforms are probably C64, Commander X16 and NES. (Possibly the BBC might be easier, but not many people are impressed by BBC games.)

Texts

Easy6502

Easy6502 is a short tutorial text that is very interesting because it comes with a 6502 emulator that runs in the web browser. The emulator supports graphics in a much simpler way than any real systems, so it’s a good way to get started and quickly see graphical results.

TokyoEdTech has made a video of himself writing some programs on the Easy6502 simulator. The first half is a good introduction; the second half is quite rambling and unprepared since he’s coding live.

There is an older version of the emulator here, which is worth checking out because it includes example programs:

Machine Language for the Commodore 64 book by Jim Butterfield

PDF

This is an excellent book for learning 6502 but is focused on the Commodore 64 and spends a lot of time explaining how to use machine code monitors, assemblers and disassemblers on that system, which isn’t required today since we can write the code on our PCs. It doesn’t actually have space to get into the useful Commodore specific stuff of generating graphics and sounds.

Famicom Party

A very nice free tutorial-style book that introduces both NES hardware and 6502 assembly.

Videos

Matt Heffernan series on Commander X16

The X16 is like a souped up, modern C64. You can’t currently buy X16 hardware, but you can learn with the emulator, and then run on real when hardware when it is available.

NESHacker on NES

NESHacker’s content is primarily videos, and they are very well produced.

If you are interested in hacking existing games as well as making your own, I highly recommend these videos, although the final one is very technical so you may want to skip it:

Hacking NES

NES Hardware

6502 Assembly on NES

ChibiAkumas

ChibiAkumas takes a very systematic approach to covering the entire subject in his many videos, as you would expect from a professional programmer mindset. This may not appeal to those with short attention spans who prefer want a tutorial with flashy results from the start and theory only introduced as necessary throughout.

ChibiAkumas is so systematic that he doesnt just cover 6502 assembly on one machine. He covers every 8 bit CPU on every machine. That’s a very completionist attitude to acquiring knowledge. To this end he provides library code that allows the same program to run on many different machines. I think this is fine (but unnecessary) during the initial stage of just learning the assembly. During the later stage of learning the machines, I suspect most will want to focus on a specific machine and so won’t use the library code.

ChibiAkumas provides a toolkit for Windows that includes a text editor, the VASM assembler, system emulators and his own library code. It gets you set up fairly quickly. However, it’s all rather… idiosyncratic. This isn’t the text editor or assembler that most people would want to use for their project. The emulators don’t include debuggers because he prefers to write his own.

If you like his style, then the videos are informative, and you can follow along using the tools, but I wouldn’t use this as the basis for my own projects.

Here’s some videos I find interesting, but you can find many more as well as text tutorials on the website:

Tools

8 Bit Workshop

8 Bit Workshop is a very impressive IDE for many 8-bit systems. It combines text editor, C compiler, assembler, debugger, sprite editor, emulator and some library code. It runs entirely in the browser so you don’t even have to install it. There some tutorial books for sale on the site, but it comes with several examples.

However, the examples and books mostly focus on C coding. I tried to write an assembly program using the CA65 assembler and it worked at first and then stopped working. Apparently the DASM assember works

CA65

This is the most popular 6502 assembler. It comes as part of CC65 C compiler.

There are binaries for Windows. For Linux you might have to compile source, unless your distro includes it in the package manager.

If you want to try older, simpler alternatives:

DASM

VASM

LLVM MOS

A fork of LLVM compiler suite that targets 6502. Getting C and similar languages to run on 6502 is not easy and so only recently has this even become usable.

Prog8

Prog8 is a high level language and compiler that is designed to be compiled to 6502 assembly much more efficiently than C. It currently supports C64 and X16 and looks to be one of the best ways of programming these systems.

FCEUX

A NES emulator with debugger. Probably the best. Binaries for Windows and Linux.

Nintaco

Another NES emulator with debugger. Nice because it’s Java so cross-platform, but that may not matter now FCEUX has been ported to LInux.

Summer Course

2021-08-08T09:00:00+00:00

Goal

Produce your own games.

Me

Those you can do, those who can’t….

Not AAA, but please buy and review!

Method

Practical - re-creating a series of my games using Godot.

Theory will also be covered as necessary.

Intro

Didn’t get replies to email to tailor course to participants… so who have we got ???
Favourite games.
Discord.
Mobiles.
VR headsets.

Git

We will use Git because:

Provides free cloud backup
Provides free hosting of webpages
It’s industry standard
(Allows team to collaborate on same project - main reason it’s used in industry)

Typing

Primary units

Platform game
- simple (kinematic) physics
- tilemaps
Space game
Racing game
- full physics
High score table
3D Godot tutorials by Kidscancode
VR wave shooter

Secondary units

Up to you which of these we do…

Keyboard skills
Analysing games
- A free game to ‘analyse’
- Another one
Python Coding
- My book
- Code combat
2d graphics:
- Krita
- LibreSpite (or Asperite)
3d graphics
- Blender - video tutorials
- Leocad
Audio:
- Music - LMMS
- Samples - Audacity or in future Tenacity
Godot Physics: Area, Static Body, Rigid Body and Kinematic Body. Similar but confusing so we should go over the differences.
Making Videos
Text Adventures:
- Part 1
- Part 2
- Part 3
- Part 4
Visual novels with Renpy
- Tutorial
Minecraft
- Playing it
- Python coding in Minecraft
- Setting up a server
- Converting minecraft buildings to Godot objects
Computer hardware
- PC Building Simulator
Linux
- Do you have a PC / laptop? Install Linux!
Finding assets
- Copyright, creative commons
- itch.io, unity store, etc
Collaborating

High Scores

2021-06-16T17:00:00+00:00

New Godot tutorial: High score table

After completing tutorial, apply it to one of your own games.

A typing tutor game: Typing of the dead

Can also continue with Vim tutorial and game analysis from last week.

Analysing Games

2021-06-09T17:00:00+00:00

To design a good new game you need to be familiar with a variety of existing games. You should get in the habit of thinking about a game while you play it, to try to understand what the designers of the game were thinking. Much like analysing a novel in English class there are many different ways to do this, so I have made a list of questions to think about while playing. You could write the answers down afterwards.

Modern games can be quite complicated, so it’s easier to start with older games. To play these you will need:

An emulator. I recommend Ludo because it emulates many different old systems.
A ROM file for each game you want to play. (Downloading ROMs may be a breach of copyright law, although it may not be if you own the game, are doing it for educational purposes, or if you download from the Internet Archive which has an exception from copyright law. Check with a lawyer who specializes in international intellectual property laws .)

Questions

Title
Year
Publisher
System
What genre(s) is the game?
What are the controls?
What style is the artwork?
What sort of music and sound effects does the game have?
What is the objective of the game?
What stops you from completing the objective?
What skills are needed to be good at the game?
What do you like about the game and why?
What don’t you like?
What would you change?
How are other (newer) games similar and different from this game?

Keyboard skills

2021-06-09T17:00:00+00:00

Posture

To avoid repetitive strain injury, you should always be aware of your posture.

Back straight.
Feet flat on floor.
Elbows bent at 90 degree angle.
Monitor slightly below eye level so neck is not bent.
Fingers lightly pressing key. Don’t hit them harder than necessary.
Relax shoulders and arms - don’t hold tension.

Look at this image at this link

Keyboard

Make sure you know the names and purpose of every key on the keyboard.

Shortcuts

Every program has different keyboard shortcuts, but some are commonly used everywhere. Make sure you know:

Ctrl-X
Ctrl-V
Ctrl-C
Ctrl-S

Touch typing

You should be able to type at a speed of 40 words per minute, or higher. You should not need to look at the keyboard while typing. The only way to learn this is to practise.

Mario Teaches Typing can help by teaching you which finger to use for which key.

Type Racer is a quick way to practise and check your speed.

Nitro Type is a fun way to compete with your friends. Click here to join the Coderdojo Loughton classroom

The Typing of the Dead

There are many other programs you can find. You could even make one yourself!

Coding

Typing code needs to more precise than when typing English. You need to get the spaces, tabs, brackets, speech marks, etc. all exactly correct. The best way to practise this is to type some programs from a book.

This is why I try to get to get you to type programs at CoderDojo, but unfortunately for longer programs we don’t have enough time and so we have to copy and paste. But you have more time at home!

Vim

Vim is a very popular text editor used by programmers. It is very different from most text editors you have used in the past such as Notepad, Mu, Godot, etc. because it is modal. It has one mode for entering text and another mode for entering commands to do things to the text. This means it takes a while to learn, but once you have learnt you can edit text very quickly.

On Linux, Vim is usually pre-installed. (Or at least the simpler version called vi). On Windows, you can install it from here.

To learn the basic keys in a fun way, first play levels 1-3 of Vim Adventures. (The first levels are free, the higher levels cost money.)

There are two tutorials that will teach you Vim.

Vim comes with a tutorial program. It is called vimtutor and on Windows it should be on the start menu.
Open Vim is good but it goes quite fast so you don’t have much time to memorise the commands. You can give it a try but you will need to do lots of practise in addition.

To practise, you could also try:

There are multiple ‘forks’ (versions) of Vim. The most popular one you could try is Neovim. Using it should be the same as using Vim. Only difference I have found is that to get the tutorial you have to run nvim and then type :Tutor rather than running vimtutor.

We’re back!

2021-05-26T17:00:00+00:00

First session this year at Multitap.

Halloween Half Term

2020-10-28T13:00:00+00:00

We need someone to video chat with Georgi.
The VR game I’ve been working on.
Download Github Desktop and makes sure you are signed up to Github so you can work at home.
Godot info to read:
Tutorials to do:
VR headsets:
- Cheap but very limited, needs a phone: Google Cardboard
- Pretty good: Oculus Quest
- Very good: Reverb G2
- Best: Valve Index
We need someone to make a poster.
Do you want a Zoom call this Saturday?

Godot Racing 4 / Gaming Club

2020-10-14T16:30:00+00:00

4.30pm Small session, invitation only, free. Should finish the project this week, what do you want to do next?

6.00pm Gaming club, open to all but email to pre-book, £3.50

Godot Racing 3

2020-10-07T16:30:00+00:00

Small session, invitation only.

Tutorial

Today:

Screen sharing (might not work)
Don’t forget to git push.
Work on own projects.
Saturday Zoom meet / gaming.
Godot documentation - hold ctrl key and click to access.
Godot has gets slow when it doesn’t like USB devices. Try unplugging and plugging into different port, especially RGB keyboard.

Godot Racing

2020-09-16T16:30:00+00:00

Small session, invitation only.

Tutorial