Veldrin
A side-scrolling game for the Amiga 500, written on the bare metal with the operating system switched off. It boots from its own floppy, on a real A500 or in an emulator, with no Kickstart ROM needed.
From Amiga Assembly
AmigaComing soon
Amiga Assembly
From the Motorola 68000 to the Amiga Hardware
Programming the Amiga, instruction by instruction
On Amazon
The Amazon link for this book is coming soon.
Every listing was assembled and run. Every figure is a photograph of a real screen.
Amiga Assembly is a complete course in programming the Commodore Amiga the way the machine was actually programmed: in 68000 assembly language, on the bare metal, with the operating system switched off and the custom chips answering directly.
It begins at the first byte — what a register is, how hexadecimal and two’s complement work, how to set up vasm, vlink and an emulator on Windows, macOS or Linux — and it ends with two finished disks that boot on a real A500: Veldrin, a side-scrolling game, and Two Hundred and Twenty-Seven, a demo with copper bars, a scroller, bobs and music.
In between: the whole 68000 instruction set with measured cycle counts; bitplanes, the display window, and the constants that differ between PAL and NTSC; four thousand and ninety-six colours, Extra Half-Brite and HAM; the Copper, a coprocessor that waits for the beam; the Blitter, its four channels and its 256 functions; eight hardware sprites and where they really land; scrolling, dual playfield, and who wins each colour clock on a bus you share with the chips. Then interrupts and the vertical blank, the CIA timers, Paula, collision detection and chip RAM discipline. Then AGA, real hardware, floppy disks, and releasing your work.
What makes this book different is that it measures. The numbers here are not copied from a data sheet. Where a figure had to be simplified, the book prints what was left out.
For anyone who can already program a little and wants to understand a machine completely rather than approximately — whether that means writing a game, joining the demoscene, or finding out what a computer looks like when there is nothing between you and the hardware.
Inside the book
- 815 pages: seven parts, 53 chapters, 12 appendices
- The whole 68000 instruction set, with measured cycle counts
- Bitplanes, the display window, PAL and NTSC, Extra Half-Brite and HAM
- The Copper, the Blitter and its 256 functions, eight hardware sprites
- Interrupts, the CIA timers, Paula and four channels of sound
- Veldrin, a side-scrolling game, and Two Hundred and Twenty-Seven, a demo — with their whole source printed and commented
- AGA, real hardware, floppy disks, and releasing your work
- 175 pages of reference: register maps, colour tables, minterms, the DMA slot table
What makes this book different
Every figure is a capture
All 244 figures were photographed from a running machine. If a figure shows a screen, the program that drew it is in the repository.
Everything is measured
Cycle counts are timed, colour tables are generated and photographed, and the DMA slot table is built from what the machine actually does.
402 exercises, all answered
Every chapter ends with workshops, and every one of them is answered in full: 37 pages of worked solutions.
No Commodore ROM needed
Everything boots under AROS, so no Kickstart image is required, redistributed or included.
Built in this book
A game and a demo, from specification to disk
Two Hundred and Twenty-Seven
A demo for the Amiga 500 in the old tradition of the scene — copper bars, a scroller, bobs and music, with its whole source printed and commented.
From Amiga Assembly
Contents
7 parts, 53 chapters
Part I Before the first byte
01The machine that arrived too early: what the Amiga is, and why it is programmed this way
02Numbers a computer understands: bits, bytes, hexadecimal, and two's complement
03Inside the case: the 68000, Agnus, Denise, Paula, the CIAs, and the memory map
04Setting up the development environment on Windows, macOS, and Linux
05Your first program: a coloured screen, assembled, booted, and photographed
06Seeing inside the machine: the emulator's debugger
Part II The 68000 language
07Registers, data sizes, and the shape of a 68000 instruction
08Moving data: MOVE and every addressing mode
09Arithmetic: add, subtract, multiply, divide, and sign extension
10Logic, bits, shifts, and rotates
11Making decisions: the condition codes, Bcc, DBcc, and Scc
12Subroutines, the stack, and the stack frame
13Tables, pointers, and position-independent code
14Counting cycles: what an instruction costs on a 7 MHz 68000
15vasm and vlink: labels, macros, includes, sections, and the executable
Part III The copper, the blitter, and the bus
16Taking the machine: switching off the operating system and taking the interrupts
17How a frame is built: two standards, 227 colour clocks, and the DMA slot table
18Bitplanes: planar graphics, bitplane pointers, and a screen you can draw on
19The display window: DIWSTRT, DDFSTRT, the modulos, and the constants that differ
20Colour: four thousand and ninety-six colours, measured
21The copper: a coprocessor that waits for the beam
22Copper lists that do real work: splits, bars, and lists that write themselves
23Extra Half-Brite and HAM: sixty-four colours, and four thousand
24Hardware sprites: eight objects, their DMA, and where they really land
25Attached sprites, sprite reuse, and priority against the playfield
26The blitter: four channels, three sources, and two hundred and fifty-six functions
27Blitter graphics: masks, shifts, cookie-cut, and a bob that moves
28Blitter fill and blitter lines
29Scrolling: fine, coarse, and a playfield wider than the screen
30Dual playfield and the priority register
31Who owns the bus: the 68000 bus cycle, and who wins each colour clock
Part IV Making it a game machine
32The vertical blank interrupt: the heartbeat of a game at fifty and at sixty
33Double buffering, and a frame that never tears
34Reading the world: joystick, mouse, the CIAs, and the keyboard
35The CIA timers: measuring time without the operating system
36Paula: four channels, eight-bit samples, period, and volume
37An engine for sound effects and music, at either frame rate
38Chip RAM discipline: where things must live, and how to place them
39Collisions: CLXDAT, bounding boxes, and detection that holds up
40Score, text, and a font drawn by the blitter
41Random numbers and game states
Part V A complete game and a complete demo
42Veldrin I: from the specification to a world that scrollsGame
43Veldrin II: enemies, sound, score, and the finished diskGame
44Two Hundred and Twenty-Seven: copper bars, a scroller, bobs, and musicGame
45Where to go next: three projects, sketched
Part VI Beyond the A500
46Fifty hertz and sixty: one game, right on both
47AGA I: eight bitplanes, twenty-four-bit colour, and HAM8
48AGA II: fetch modes, wider sprites, and what breaks when you move up
49Optimisation: cycles, chip RAM, and the tricks that buy both
Part VII Giving the machine back
50Living with AmigaOS: opening a screen, and giving the machine back
51Loading from disk: the bootblock, trackdisk, and a loader of your own
52Testing on real hardware: real A500s, real monitors, real floppies
53Releasing your work: disk images, WHDLoad, and the scene today
Appendices
- AThe 68000 instruction set, with measured cycle counts
- BCustom chip register map: Agnus, Denise, Paula, PAL and NTSC
- CCIA register map and timer tables
- DColour tables: OCS/ECS 4096, EHB, HAM6, and AGA 24-bit
- ECopper and blitter reference: the 256 minterms and the slot table
- Fvasm, vlink, and emulator command reference
- GTroubleshooting: what a broken screen is telling you
- HWorkshop solutions, every chapter
- IGlossary and reading paths
- JVeldrin: the complete source, commented
- KTwo Hundred and Twenty-Seven: the complete source, commented
- LIndex
Errata
Corrections
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