Showing posts with label emulator. Show all posts
Showing posts with label emulator. Show all posts

Tuesday, 25 November 2014

Rocket Raid Under The Hood 2: Disassembly Tools and References

This is the second part in a series of posts on digging into the code of the Acornsoft side-scrolling arcade game, Rocket Raid.

There are a number of tools that we will need in order to dig into the code of Rocket Raid, and some books that will come in handy.

Software Tools


First is a BBC Emulator for running the game and for its debugger/monitor feature which allows memory locations to be updated on the fly. I will be using the excellent BeebEm.

The disassembler BeebDis, by Phil Harvey-Smith, allows game code to be turned back into assembly language instructions for closer examination. Not only that, but the assembly instructions can be modified for reassembly which will be very useful for investigations.

BeebAsm, by Rich Talbot-Watkins, is an assembler which will allow assembly code to be assembled into machine code for running on the emulator. The BeebDis assembler produces code in a format that is compatible for feeding into BeebAsm.

BBC Explorer by Laurie Whiffen. This easy-to-use GUI-based utility allows the contents of a BBC disc to be extracted into individual files, and is compatible with various emulated disc formats.

Reference Material


The Advanced User Guide
One useful reference manual is the BBC Advanced User Guide, which can be downloaded from here. This guide was the companion to the standard User Guide for the BBC, and contains a wealth of information including operating system calls, memory locations and assembly language instructions.










Creative Assembler
 by Jonathan Griffiths
As mentioned in the previous post, Jonathan Griffiths wrote a book called "Creative Assembler - How To Write Arcade Games" which is available online here. Inside are a number of assembly-language routines with comments by the author which will hopefully help shed light on some of the code found in the Rocket Raid game.








And Last But Not Least...

And of course we will need to obtain a disc image of the game itself, which can be found on various websites such as Stairway To Hell.

Sunday, 4 August 2013

BeebEm - a BBC Micro Emulator

To run the old BBC games on my PC, I use the emulator BeebEm which is very easy to set up and run. You can download and install it from the BeebEm homepage.

One nice thing about using an emulator to run the games is the extra functionality it provides which wasn't available when running on the original hardware, such as the ability to redefine keys or save the state of a game at any point.

The other thing needed is disk image files with software to run. A site which has a vast collection of BBC software is Stairway to Hell.