[Coco] modular

[Roger Taylor]

P-3's scheme is not as useful as yours, but I did make it check to see if 
the module (codec driver) is already in RAM before loading it from disk.

Speaking of tricks, here's a trick for single-drive users, since P-3 
requires 2 drives... you can still use the program by inserting a picture 
disk in Drive 0 then click on the filename (which loads the entire file), 
and when the error pops up that the format driver can't be found, reinsert 
your P-3 disk, and hit the [SPACE] key.  This causes the codec only to be 
loaded, not the picture file again.  The codec takes over, reading the 
picture file that was loaded.

...anyway...





At 04:28 PM 10/26/2003 -0500, you wrote:
>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.
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco