[Coco] Creating and loading big machine code files into RSDOS

[Mark McDougall]

On 14/02/2017 9:48 AM, Glen Hewlett wrote:

> Is there an easy way that doesn’t require me to make my own disk
> loader program?  It would be amazing if such a feature was built in
> to lwasm.

Here's what I've done in the past... keeping in mind that my development 
is done on a PC and the build process creates a floppy disk image as one 
of its outputs.

For binary data, it's relatively trivial to write a quick C program that 
takes a raw binary chunk of data and turns it into an RSDOS .BIN file 
that self-loads directly into whatever page(s) of memory you like. 
Essentially all you need to do is inject a handful of bytes into the 
file at strategic points and save it as a .BIN file. I'd suggest you run 
this program each time as part of your build process, so that you may 
modify your raw data file at will throughout development.

For the code, you can do exactly the same, as long as your starting 
point is a raw binary image of the assembled code, and not a .BIN file. 
If that's not possible, technically you can actually modify the existing 
.BIN file, but it's easier to start with a raw image.

I always found this the most convenient as there's no stuffing around 
with loaders and such, aside from a 2-line BASIC loader that LOADM's 
your data and then your code. Written properly and part of the build 
process, it's still possible to resize and move data around, for 
example, and not have to change your 'loader' code at all.

In your case, with more than 32KB of binary, it's a little different but 
for Lode Runner (demo) and Knight Lore, both less than 32KB, a single 
(raw) binary image gets assembled at $8000. That becomes the cartridge 
image, and then the above-mentioned C program is run on it to create a 
single .BIN file that is subsequently loaded from floppy. The advantage 
is the exact same build for both cartridge and floppy versions; less 
configuring and no chance of bugs on one format that don't appear on the 
other!

Let me know if you want any more details on any part of the process.

Regards,

-- 
Mark McDougall
<http://retroports.blogspot.com.au>