Toward the end of the of last month’s RetroChallenge I started looking at TurboForth. I was impressed with the TurboForth game Dark Star. I thought it would be fun to make my own game. I used Dark Star as example code to get my game started. I borrowed the rock tiles and the routines to draw them.

This new game is called TI Fighter. It is inspired by Street Fighter from 1987. My son, Josh, is into retro games and is helping with the game design and graphics. Currently the game requires two joysticks. Since development has just started at this time you basically can just move the characters around and kick. No collision is detected yet.

Here is a couple of snapshot of what we have so far.

In this series of post I plan to blog about the development of this game.

Running the Game

The source for TI_Fighter is on github. Basically there are three files:

• ti_fighter.fs : This is the source for the game written in TurobForth.
• FIGHTER : This is the “block file” version of the source that can be loaded by TurboForth.
• move.py : This is a python script I wrote to convert ti_fighter.fs into the block file FIGHTER.

Using TIPI

I am using TIPI as my disk solution for my TI-99/4A. Using TIPI I am able to ssh into Raspberry Pi that is hosting the tipi_disk. Then from the tipi_disk directory I clone out the TI_Fighter repository.

pc> ssh tipi@tipi
...
tipi> cd tipi_disk
tipi> git clone git@github.com:bblodget/TI_Fighter.git

I then update tipi.config to have DSK3_DIR set to TI_Fighter. After you update the tipi.config you need to reboot the PI. Here is the top three lines from my tipi.config:

DSK1_DIR=TurboForth122.DSK1
DSK2_DIR=TurboForth122.DSK2
DSK3_DIR=TI_Fighter

The TurboForth122 DSK1 and DSK2 files I got from the TurboForth Download page.

Then from the TI-99/4A I start TurboForth and type:

S" DSK3.FIGHTER" USE
1 LOAD
FIGHTER

After you get the game started it is probably best to “depress” the ALPHA LOCK key, so the joysticks work correctly.

To break out of the game hit any key on the keyboard.

Using Classic99 Emulator

The Classic99 Emulator is a TI-99/4A emulator for Windows. It comes with TurboForth as one of the built-in cartridges.

To get TI_Fighter installed simply copy the block file FIGHTER into DSK3 folder. You can then load the game from TurboForth in the same way:

S" DSK3.FIGHTER" USE
1 LOAD
FIGHTER

In Classic99 you can go to Options->Options to set the Joystick configuration. If you select “PC Keyboard” to emulate a Joystick use the arrow keys to move, and Tab to fire.

Development

My current development flow is to ssh into the TIPI Raspberry Pi and use vim to edit ti_fighter.fs. Then I run the move.py to copy the data over to the FIGHTER block file. Then from the TI I type:

RELOAD
1 LOAD
FIGHTER

The file ti_fighter.fs starts with the following:

FORGET -->>

: -->> 0 EMIT [COMPILE] --> ; IMMEDIATE

: Reload ( --)
    \ Reloads FIGHTER block file
    S" DSK3.FIGHTER" USE
    ;

The first line “FORGET –»” says forget the word “–»” and all words created after it.

The word “–»” basically says compile the next block in the block file. Every block in the block file FIGHTER ends with the the word “–»” to load the next block. That way you can load the whole game using “1 LOAD”.

The word “Reload” reloads the block file “FIGHTER”. When you type “1 LOAD” the first thing it does is forgets the previous definitions and then redefines them all.

I find this development flow easier than trying to type using the TurboForth’s block editor.

But there is probably a better method….