[Coco] 6309 microprocessor project - 10-24-2003

[KnudsenMJ at aol.com]

In a message dated 10/25/03 10:42:20 PM Eastern Daylight Time, 
rtaylor at bayou.com writes:

> Projector-3, and Mike K's UltiMusE use similar methods of allowing programs 
>  much larger than 64k to be run.  Mike's program runs under OS-9.  Mine is 
a 
>  DECB program that uses it's own memory mapping scheme.  Both programs are 
>  really only limited to a size determined by the floppy disk or hard drive 
>  they are stored on.  They could grow "forever" ...

"Forever" only if the master program knows to unlink (remove from RAM) 
modules that are currently not in use, when their space is needed to load and link 
other modules.  To save my figuring out how to do this "paging" (the subject of 
much intensive academic study in the 60s and 70s), and as a convenience to 
the user, UltiMusE leaves the subroutine modules in RAM once they've been loaded 
the first time.  So every time you go to play the music, you don't wait for 
the disk to grind and load the play module.

Remember "Sub Battle Simulator" and some other Tandy Coco3 OS9 games?  That 
kept reloading the same modules over and over?  Yes, so they'd work in 128K.  
But there should have been a user option, or sensing for 512K!

If anyone REALLY wants to see the source code for how I did the subroutine 
modules and virtual data memory, I will post the stuff, and help someone figure 
out how it works.  My subroutine module calling system is really flexible.
--Mike K.