This is a quick documentation file on the machine language graphical text driver CHARGEN 
used by both Galactic Revolution and Galactic Conquest. It shows you how to load it for 
your BASIC programs, and how to use some special features it has (and a couple of things 
that work a little differently than regular BASIC).

CHARGEN brief documentation:

CHARGEN is a small assembly language routine that interfaces with BASIC so that 
you can use it in your BASIC programs. It runs on a PMODE 4,1 screen and is 
currently set up for a disk system (There are some POKE's that can be done to 
make it work with cassette; see the Galactic Revolution program loader REVOLT.BAS 
to see what to change). 

It supports true upper & lowercase with a pre-bolded font to make it easy to read 
even on a TV. It also gives you 32x24 text, letting you fit up to 768 characters 
on the screen at once versus the normal BASIC 512. It also features a few special 
CHR$ commands that you can PRINT:

    CHR$(8)  - Backspace
    CHR$(12) - clear screen and home cursor
    CHR$(13) - Carriage return
    CHR$(14) - Turn cursor on
    CHR$(15) - Turn cursor off
    CHR$(16) - Turn inverse on
    CHR$(17) - Turn inverse off
    
There are also special features that are controlled bye POKE's to certain memory locations:

    POKE &HDC,(0-31): Set cursor X position
    POKE &HDD,(0-23): Set cursor Y position
    POKE &H200,(0-30): Set "window" area left position
    POKE &H201,(0-22): Set "window" area top position
    POKE &H202,(1-32): Set "window" area X size
    POKE &H203,(1-24): Set "window" area Y size

By setting the values at &H200 to &H203 you can set up a special "window area" that text will 
scroll within (good for things like adventure games).

To use it currently requires a 32K RAM or higher Coco 1,2,3. You will need to do the following 
to load it:

    CLEAR 200,&H79A8
    LOADM "CHARGEN"
    EXEC
    
After that, you can write you BASIC program, and mix PMODE 4 graphics commands with text.

NOTE: Only characters from 32 to 127 are defined (CHR$). Any values above that will print 
out some garbage (maybe you can use them for exploded items or something).