mirror of
https://github.com/hsoft/collapseos.git
synced 2024-11-17 10:38:05 +11:00
74 lines
3.3 KiB
Markdown
74 lines
3.3 KiB
Markdown
# Assembling Collapse OS from within it
|
|
|
|
This is where we tie lose ends, complete the circle, loop the loop: we assemble
|
|
a new Collapse OS *entirely* from within Collapse OS and write it to EEPROM,
|
|
either for another RC2014 or for an OS upgrade.
|
|
|
|
## Gathering parts
|
|
|
|
* stage3 from `sdcard` recipe. If you want to write to EEPROM as the final step,
|
|
you'll need a hybrid stage3 that also includes stuff from the `eeprom` recipe.
|
|
|
|
## Building the binary
|
|
|
|
Build Collapse OS' from within Collapse OS is very similar to how we do
|
|
it from the makefile. If you take the time to look at the base recipe
|
|
`Makefile`, you'll see `cat xcomp.fs | $(STAGE)`. That's the thing. Open
|
|
`xcomp.fs` in a text editor and take a look at it. You'll see that it loads
|
|
B618, which contains the meat, and then spits stuff to port 2, which is a
|
|
special signal for the `stage` binary.
|
|
|
|
To assemble from RC2014, all you need to do is load B618. This will
|
|
yield a binary in memory. To know the start/end offset of the binary, you'll
|
|
type the same two commands and in `xcomp.fs`, but replace the `/MOD 2 PC! 2 PC!`
|
|
words with `.X`. Then, write that binary between those offsets on your target
|
|
media. That binary should be the exact same as what you get in `os.bin`
|
|
when you run `make`.
|
|
|
|
Go ahead, run that. However, one thing you should know is that because the SD
|
|
card driver is a bit slow, some of these commands take a long time. Multiple
|
|
minutes. Be patient.
|
|
|
|
Is that it? Yes. But for your own enlightenment, open B618 and look at it, I'll
|
|
give you an overview of its contents. I'm not going to explain in detail what
|
|
each command do, however. You are encouraged to read the in-system
|
|
documentation for more information.
|
|
|
|
The first part is configuration of your new system. When RAM starts, where RSP
|
|
and PSP start, what ports to use for what device, etc. These configuration
|
|
declarations are expected in the boot code and driver code.
|
|
|
|
Then, we load the Z80 assembler and the cross compiler (xcomp for short), which
|
|
we'll of course need for the task ahead.
|
|
|
|
Then come xcomp overrides, which are needed for xcomp to be effective.
|
|
|
|
At this point, we're about to begin spitting binary content, this will be our
|
|
starting offset. `ORG` will soon be set to your current `H@`.
|
|
|
|
Then, we assemble the boot binary, drivers' native words, then inner core,
|
|
close the binary with a hook word. We're finished with cross-compiling.
|
|
|
|
We're at the offset that will be `CURRENT` on boot, so we update `LATEST`.
|
|
|
|
Then, we spit the init source code that will be interpreted on boot.
|
|
And... that's it!
|
|
|
|
### What to do on SDerr?
|
|
|
|
If you get `SDerr` in the middle of a LOAD operation, something went wrong with
|
|
the SD card. The bad news is that it left your xcomp operation in an
|
|
inconsistent state. The easiest thing to do it to restart the operation from
|
|
scratch. Those error are not frequent unless hardware is faulty.
|
|
|
|
### Verifying
|
|
|
|
You can use `/tools/memdump` to dump the memory between your begin/end offsets
|
|
so that you can compare against your reference stage 1. Before you do, you have
|
|
to take yourself out of xcomp mode. First, run `XCOFF` to go back to your
|
|
regular dict. Then, run `FORGET CODE` to undo the xcomp overrides you've added
|
|
before. That will rewind `HERE`. You don't want that. Put `HERE` back to after
|
|
your ending offset so that you don't overwrite your binary.
|
|
|
|
Then, you can run `/tools/memdump`.
|