Presenter99

Presenter99 is a slideshow engine written in BASIC for the TI-99/4A.

Usage

Slideshows are encoded in the engine program as DATA commands between lines 1-1899. Simply edit template.bas and run make to generate presenter99.bas. This program can be copied into an emulator such as Classic99. Exporting to WAV files for cassette storage is planned.

Format

A slideshow is encoded as a series of events. Each event consists of an opcode and a list of arguments.

The first event is always TITLE, which sets the presentation's title, subtitle, and default foreground and background colors:

10 DATA "TITLE","My Presentation","Charles Averill",16,2

This data will be rendered as a title slide.

The remainder of the slideshow consists of slides, delimited by SLIDE events. Each SLIDE event denotes a new slide with a given title:

20 DATA "SLIDE","Slide 1"

Within each slide can be any number of events. A table of their effects is provided below.

Event	Effect	Example
TEXT	Draw left-aligned text that may wrap around the screen	30 DATA "TEXT","Here is some text"
LIST	Draw an unordered list	40 DATA "LIST","First","Second","Third","END"
SPACING	Print N empty lines if N>=0, or print until the screen is almost full (for printing footers) if N=-1	100 DATA "SPACING",-1
COLORS	Update the foreground and background colors, will take effect on slide transition	50 DATA "COLORS",5,16
PAUSE	Pause in the middle of a slide	95 DATA "PAUSE"
BIGIMG	Denotes an image slide (see below). Title appears while characters are loading	180 DATA "BIGIMG", 20, "TI-99/4A"

Images

The BIGIMG token denotes two series of data:

1. A sequence of custom 8x8 character definitions to be passed into CALL CHAR
2. A run-length encoded (RLE) sequence of characters to fill the screen

Although possible, it's not recommended to generate these by hand. imgconverter.py will take in an image file, a starting BASIC line, and a maximum number of characters, and generate a BASIC file with the encoded image.

Images are monochrome. This could be adjusted, as characters occupy four groups of 8, so CALL COLOR could assign unique foreground and background colors to each image. This would require some pretty hefty modification of the conversion script though.

Even with RLE, these images are very large. The template barely fits two in. Perhaps a future version will support loading from disks or cassettes.

Original Image	Converted Image	Encoded Image
		shapes.bas
		ti99.bas