[Coco] DECB USRn function?

[Robert Gault]

Mark McDougall wrote:
> Hi,
> 
> Does anyone know how to pass an argument to a ML routine using USRn?
> Also, how does one return a value to DECB?
> 
> I can't find any useful doco in the user manuals, and a quick perusal of 
> the
> 'unwravelled' books didn't enlighten me. :(
> 
> TIA
> Regards,
> 

You did not specify where you looked so I can't tell what manuals you 
own but you should have dug deeper. :)

Getting Started with Color Basic
p268 - USR example    110 A=USR(0)
"Note: On entry to the subroutine, you can get the USR argument (the 0 
in this case) by calling a ROM subroutine, INTCNV, which returns the 
integer value in the D register. The address of INTCNV is $B3ED."

Going Ahead with Extended Color Basic
p 145-150 More details enhancing Basic with ML programs and passing 
variables back and forth.

Color Computer3 Extended Basic
p 232-233 Explains USR but not how to pass variables.

It is easy to find INTCNV and the inverse GIVABF plus other useful 
routines by looking in the "Basic Routines and Entry Points" appendix.