[Coco] Copying a data/binary file from disk to cassette

[Phil]

Robert Gault wrote:

>About your only option using Basic would be CSAVEM which will dump 
>data to cassette without making any changes. So, the disk data file 
>will need to be opened and stored into known memory. Let's say for 
>example, you POKE the data into memory starting at $3000 and 
>continue to the end of the file. Then you 
>CSAVEM"name",&H3000,&H3000+length,0. To use the data, you would 
>CLOADM"name" and process the data stored at $3000.

This was actually my original plan, but when I'm dealing with a .bin 
that I've just LOADMed into memory without qualifiers, I don't know 
how to ascertain the right start and execution points (which is why I 
was hoping to avoid the whole thing by doing a straight copy).  For 
instance, I have a .bin of Downland* that runs fine in emulation with 
a straight LOADM "DOWNLAND.BIN", but I don't know what I'd need to 
dump, post-LOADM, into my CSAVEM.  Is there a reliable way of finding 
that out?  Surely there must be something in the headers that tells 
LOADM where to put things, no?

Best,
Phil

*a program I actually do own on cart, though I have no idea where it went to!