Programming adventures in VIC-20.

Pursuing Tom Ram. Development guide

The goal of this guide is helping you in learning and writing games in assembly for Commodore computer family (mainly VIC-20) and, specially, text adventures. Almost everything works for a Commodore 64. You will find the changes for a C-64 at the end of this guide.

This development uses the Student Edition of the adventure Pursuing Tom Ram ( source code in Github. ). There are little changes between Student Edition and the final version. Final version drop some unused codes and add extra code for including EAt command (so, you EAT LEAF instead of PUT LEAF).

If you found gaps in this guide, let me know.

There is a similar guide about Desert, a grid-game created form the code of Pursuing Tom Ram.

Index

• Previous knowledge

• My experience

• Rom subroutines

• How I use page 0

• Storing information

• The main loop

• Printing things

• Printing objects

• Input

• Understanding input I. Break into pieces

• Understanding input II. Do I know you?

• Checking verb and name

• Movement I. The map

• Movement and exits

• Movement verbs

• Movement Improved

• Inventory

• Hidden objects

• Flags

• Verb Examine

• Chains

• Objects you can take and objects you do not

• One puzzle. Diary

• A problem with the branches

• How to add a new verb

• Synonymous

• Memory

• More Memory

• Portability to Commodore 64

• Portability to PET / Commodore-16

• Portability to other 6502 systems

Have fun.