collapseos/recipes/rc2014/zasm

Assembling binaries

For a system to be able to self-reproduce, it needs to assemble source z80 assembly to binary.

Goals

Have a RC2014 assemble a Collapse OS kernel with its source living on a CFS on a SD card.

Work in progress: for now, we compile a simple hello.asm source file.

Gathering parts

• Same parts as the SD card recipe.

The zasm binary

To achieve our goal in this recipe, we'll need a zasm binary on the SD card. This zasm binary needs to be compiled with the right jump offsets for the kernel we build in this recipe. These offsets are in user.h and are closely in sync with the configuration in glue.asm.

user.h is then included in apps/zasm/glue.asm.

The makefile in this recipe takes care of compiling zasm with the proper user.h file and place it in cfsin/zasm

The userland source

The code we're going to compile is cfsin/hello.asm. As you can see, we also include user.h in this source code or else ld hl, sAwesome would load the wrong offset.

Because of this, the Makefile takes care of copying user.h in our filesystem.

Preparing the card and kernel

After running make, you'll end up with sdcard.cfs which you can load the same way you did in the SD card recipe.

You will also have os.bin, which you can flash on your EEPROM the same way you already did before.

Running it

Compiling and running hello.asm is done very much like in the shell emulator:

Collapse OS
> sdci
> fson
> fopn 0 hello.asm
> zasm 2 1
> mptr 8600
> bsel 1
> seek 00 0000
> load ff
> call 00 0000
Assembled from a RC2014

That RC2014 is starting to feel powerful now, right?