ATALAN Atari platform

Introduction

Basic memory layout

Supported data types

Printing

Fonts

Interrupts

VBI

DLI

Commands

DOS

wait'line

Introduction

This document describes standard ATALAN library for ATARI 8-bit platform. Some parts of this text require good knowledge of ATARI platform.

Basic memory layout

Application starts at $2000. When it ends, infine loop is performed. If you want to exit to DOS, execute DOS command at the end of application.

Variables are placed in zero page starting from address 128.

Supported data types

Printing

Printing strings is done using standard OS routine. When printing into arrays, it is supposed the array is displayed on screen and conversion to ATARI screen codes is performed.

Fonts

Interrupts

It is possible to write interrupt routines directly in ATALAN. Compiler will create appropriate code to

VBI

VBI procedures are executed every frame (1/50s on PAL, 1/60 on NTSC). Defered VBI is used (consult ATARI ROM manual to understand what it means), so hardware registers must be used to change colors etc.

VBI procedure must be of type VBI. It takes no arguments.

To activate the interrupt, use on'vbi procedure.

cycle'color:vbi = inc COLOR0(5) COLBK = COLOR0(5) ;as we are using deferred VBI, we must copy the color to hardware register on'vbi cycle'color

DLI

Commands

DOS

Exit to DOS

wait'line

Wait for the end of current scan-line. (Performs sta WSYNC).