[Coco] Random Numbers in 6809 assembly

[Roger Taylor]

At 04:41 AM 12/30/2004, you wrote:
>Please also note that I'm using good-old fashioned disk edtasm, as for some
>reason portal-9 doesn't cooperate with my computer, and when I use cm.exe I
>cant import the binaries properly to virtual coco disks.. life's tough :P
>
>If anyone can help with a random number generating routine, it would be
>wonderful!
>
>Thanks
>David R


What problems are you having with Portal-9?  This is probably something 
you're overlooking.

Make sure you enter a filename into the "output filename" field in the left 
panel, so that the IDE can control what CCASM outputs as the binary 
program's filename.  This way, the same name can be passed to the 
IMGTOOL.EXE utility which will import the file onto the virtual 
disk.  Otherwise, entering no name in the "output filename" field will 
cause CCASM to create a default filename for the output file.  This is 
usually {sourcefile}.bin, but we need to force a name so that all involved 
tools are aware.

Generating a psuedo-random number sequence can be as easy as choosing a 
starting number (0-65535), then for each generation, do something like LDD 
SEED, multiply x 13709, ADDD #13849, STD SEED.  The seed can also be a CPU 
address, like the start of the ROM memory, and you can peek each address 
for your random number, but perform other actions on the values.

-- 
Roger Taylor