collapseos/doc/zasm.md

Assembling z80 source from the shell

In its current state, Collapse OS has all you need to assemble z80 source from within the shell. What you need is:

• A mounted filesystem with zasm on it.
• A block device to read from (can be a file from mounted CFS)
• A block device to write to (can theoretically be a file, but technical limitations temporary prevents us that. We'll use a mmap for now).

The emulated shell is already set up with all you need. If you want to run that on a real machine, you'll have to make sure to provide these requirements.

The emulated shell has a hello.asm file in its mounted filesystem that is ready to compile. It has two file handles 0 and 1, mapped to blk IDs 1 and 2. We only use file handle 0 (blk ID 1) and then tell zasm to output to mmap which is configured to start at 0xe00

Collapse OS
> fopn 0 hello.asm      ; open file in handle 0
> zasm 1 3              ; assemble opened file and spit result in mmap
> bsel 3                ; select mmap
> peek 5
210890CD3C              ; looking good
> mptr 4200             ; hello.asm is configured to run from 0x4200
> load ff               ; load compiled code from mmap
> peek 5
210890CD3C              ; looking good
> call 00 0000
Assembled from the shell
>                       ; Awesome!