diff options
Diffstat (limited to 'baremetal')
| -rw-r--r-- | baremetal/boot.hex | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/baremetal/boot.hex b/baremetal/boot.hex index ef14651a..9ae9a7c8 100644 --- a/baremetal/boot.hex +++ b/baremetal/boot.hex @@ -21,8 +21,8 @@ # # Since we start out in 16-bit mode, we need instructions SubX doesn't # support. -# This file contains just lowercase hex bytes and comments. Zero -# error-checking. Make liberal use of: +# This file contains just lowercase hex bytes and comments. It makes liberal +# use of: # - comments documenting expected offsets # - size checks on the emitted file (currently: 6144 bytes) # - xxd to eyeball that offsets contain expected bytes @@ -32,6 +32,14 @@ # - can't print text to video memory (past these boot sectors) # - must only print raw pixels (256 colors) to video memory (resolution 1024x768) # - must start executing immediately after this file (see outline below) +# +# Don't panic! This file doesn't contain any loops or function calls. 80% of +# it is data. One pass through less than 1KB of code (there's lots of +# padding), and then we jump into a better notation. The rest of the stack +# (really only in a couple of slightly higher-level places) only needs to know +# a few magic constants: +# Video memory: start is stored at 0x7f28 +# Keyboard buffer: starts at 0x7ee0 # Outline of this file with offsets and the addresses they map to at run-time: # -- 16-bit mode code |