Boulder Dash for the Oric

This is a fan-developed version of Boulder Dash for the Oric (Oric-1 or Atmos). I thought it would be a good way of getting to find out more about the Oric-1 I recently purchased by porting the BBC/Acorn Electron version of Boulder Dash to this platform.

This repo really contains 6 different versions of the game. They all run with the same 'game engine' but have different caves. Select the version to play from the splash screen.

• Boulder Dash, Boulder Dash 2 and Boulder Dash 3, are similar to the original games released for other platforms in the 1980's.

• Boulder Dash +1 contains two main enhancements not in the other versions, the use of bombs and having zero-gravity caves.

• The Arno Dash games are some examples of the many fan-developed caves found on Arno's Boulder Dash fansite. Boulder Dash format files (BDCFF) are used to create new caves which run with the game-engine.

Oric-1, Atmos and emulation

Oric Boulder Dash is available in the tap folder.

The quickest way to give it a try is via the JOric emulator. More about this emulator is available here.

It has been tested using the Oricutron emulator and on a real Oric-1. The game TAP file was loaded via the excellent LOCI device. This device also allows the Oric-1 to use the Atmos ROM v1.1 so although the game works with both the Oric-1 and Atmos, the default build is for the Atmos. See the simple steps below to switch to an Oric-1 build.

There are some differences in this Oric version of the game, although they do not affect the main game play.

• Bombs and zero-gravity enhancements. These are only used in caves where they have been defined as cave parameters (see below for more details).
• The status bar is different as it shows the diamonds needed, reduced each time one is gathered. The diamond value is not shown. A count of the number of bombs available is included, as are the normal things such as time remaining, lives available and the player score.
• Future improvements being considered are the ability to choose the keys to use for up-down-left-right and fire. Joystick support might be an option via the LOCI device. Lower down the list are possibly having a demo mode, overall high score and support for 2 players.

Keys used

• The version to play is selectable from the splash screen using the up-down arrow keys and pressing the space bar.
• Both the cave and difficulty level are selectable from the main screen using the up-down, left-right arrow keys. Pressing the space bar starts the game.
• Different colour schemes are selectable using the "<" and ">" keys.
• There is a choice of using the standard up-down, left-right arrow keys for navigation within the game or an alternate layout where the arrow keys on the left of the space bar are up-down and the arrow keys on the right are down-up (this feels more natural to me on a real Oric!). Pressing the left-shift key on the menu screen toggles between having standard or alternate keys.

• In the game, the direction keys are used to navigate Rockford around the cave. Holding down the space bar and pressing a direction key lets Rockford push a rock, clear a space, plant a bomb or grab a diamond, all without moving.

• The greater-than key > will pause the game. Pressing left-shift will kill Rockford (needed if trapped).

• The game comes with instructions which explain the main characters and features.

Developer notes

• The osdk_config.bat script lists the assembler files used to build the game.
• The bd_build_all.bat script uses this config information and compiles main.s using the OSDK make.bat command which in turn uses the xa.exe assembly-language complier, linker and header.exe to make the game a loadable TAP file.
• The sprites are created as a separate TAP file, by assembling spr.s, adding a TAP header and naming the TAP file using taptap.exe.
• A splash screen TAP file is created using pictconv.exe, given a TAP header and name.
• The caves for each game version are combined then created as separate TAP files. Individual caves are found in caves_bin. These are already binary files and are combined into a single file, assigned a TAP header and name.
• The game, sprites and caves for all versions are all combined into a single TAP file to load on the Oric. The order of these files is important as the program does not rewind the tape to find the TAP file to load!

Caves

• All 20 caves are available in memory (16 standard and 4 bonus caves). They each have the same size, 48 bytes used for parameters, 400 bytes for the map. Each tile in the map is a nibble (each byte represents two tiles). When a particular cave is about to be played, it is loaded into a section of memory labelled cave_parameter_data. See cavedata.s for more details about the parameters available.
• New cave files can be converted from BDCFF files found on Arno's Boulder Dash fansite using a conversion utility BDCavegen.py found in the utilities folder.

Switching between Atmos and Oric-1

By default this game runs on the Oric Atmos but is easy to build for an Oric-1 instead. Amend the machine setting in bd_build_all.bat to be set MACHINE=oric1, and repeat in the run script bd_run.bat.

Switching between single row and full matrix keyboard

Although a single row keyboard is used (just having the arrow keys, space bar and a few other keys), a full matrix keyboard can be used instead. With some further development a choice of keys could be provided to users. The steps needed to switch are as follows.

• Amend osdk_config.bat, comment / uncomment keyboard requirement.
• Amend main.s, comment / uncomment #define full_matrix_keyboard.
• Amend bd_build_all.bat, comment / uncomment CAVEADDR requirement (the full matrix keyboard is a larger program, and changes the address where the caves are loaded).
• Run bd_build_all.bat to compile and create caves.tap with correct load address.

Acknowledgements

The following sources have all helped to make this development possible and is gratefully acknowledged.

• The OSDK is a fantastic source for all things Oric development-related. The articles and samples were especially helpful.
• The keyboard read routine available via the OSDK makes it easy to add effective keyboard handling into a game.
• The Defence Force forum is a great source of information. The sound fx generator was used to create the sound effects. The Oric Boulder Dash chat has guided further development with helpful input from Oric experts.
• The book Oric Atmos and Oric 1 Graphics and Machine code techniques available for download from the Oric library is a wealth of handy information.
• The disassembly of the original BBC/Acorn Electron game by TobyLobster was where this all started.
• Arno's Boulder Dash fansite