Disassembly

I am in the process of disassembling Wicked using Aira Force and Ghidra.

I cannot recommend AiraForce highly enough for disassembling Amiga Games. It is brilliant. My thanks to Howard Price for all the help and support with AiraForce, and for integrating some small requests into his program to really help me with disassembling Wicked. Go grab that from https://howprice.itch.io/aira-force

To disassemble with AiraForce, we need an uncompressed binary. There are two versions of the game that were released.

IPF-1263 – The Intro/Loader is encrypted, but the game is not
IPF-0295 – Both the Loader/Intro and the game are encrypted

Wicked used the Rob Northen Copylock protection system, to prevent causal piracy, so we are not able to use the hunk files from the original disk. Back in 1989, software piracy – particularly for the Amiga – was rife, and within a day of the game’s release, Wicked had already been cracked. These cracks removed the protection, so in the ‘work smarter, not harder’, we can use the compressed binary from the Oracle crack, decompress it with xfddecrunch on an Amiga, and we end up with an uncompressed binary to load in to AiraForce, beginning at memory location $27FF2 with a size of $57B3E (359,230) bytes.

I do own a legitimate, original disk of the game that I have had since I was fifteen (and also the dual format coverdisk that came with Zero magazine issue 11 (September 1990). Here’s a photo of me doing my best Kickstart 1.3 impression.

Interview with Paul Norris in Freeze64 Issue 77

There is a new interview with Paul Norris in the current issue of Freeze64. Whilst the issue predominantly features the game Zoids (an earlier Commodore 64 game that he wrote), the interview does include a section devoted to Wicked. You can get the issue from https://freeze64.com/freeze64-issue-77/

Sound effects event system

Previously, I thought a way to uncover what was happening in the code in Wicked was to look at the sound effects and tie the sounds to when they were triggered. I was left looking at where the value of D0 was set, and this led me into discovering the event signalling mechanism in Wicked. […]

Manhattan Distance

The way growth spreads in Wicked has always fascinated me. Ever since I read that the four types of growth have different ‘intelligences’ in the player’s guides, I’ve wanted to figure out exactly how it works. Now, after digging into the game’s code, I’ve tracked down the growth routine, and with some help from Aira […]

Disassembling with AI

It’s been a busy couple of weeks at work, and so I’ve not been able to spend much time with the disassembly. I decided to experiment with ChatGPT to see if that could give me a speed boost. Obviously, the dream would be to outsource all the effort to a tool that could quickly and […]

Using sound effects to identify routines

My next idea for identifying blocks of code comes from the idea that when an event happens in the game, a sound effect is usually played – for example, when shooting, there is a “shooting” sound effect. If I can figure out the addresses of the sound effects, it might be a clue as to […]