Instantly share code, notes, and snippets.

Embed
What would you like to do?
68k Mac boot floppy example
#!/bin/bash -xe
m68k-unknown-elf-gcc -o demo demo.s -nostdlib
m68k-unknown-elf-objcopy -O binary demo floppy.img
# 68k Mac boot floppy example
#
# Boot block header based on first/first.S
# from http://emile.sourceforge.net/
#
# More resources:
# http://www.mac.linux-m68k.org/devel/macalmanac.php
# http://www.pagetable.com/?p=50
# Linux and BSD kernel source, e.g.
# https://github.com/torvalds/linux/tree/master/arch/m68k/mac
# The ROM loads this many bytes from the start of the disk.
.equ stage1_size, 1024
# Macro to define a Pascal string
.macro pString string
pstring_begin_\@:
.byte pstring_end_\@ - pstring_string_\@ - 1
pstring_string_\@:
.string "\string"
pstring_end_\@:
.fill 16 - (pstring_end_\@ - pstring_begin_\@) , 1, 0
.endm
begin:
ID: .short 0x4C4B /* boot blocks signature */
Entry: bra start /* entry point to bootcode */
Version: .short 0x4418 /* boot blocks version number */
PageFlags: .short 0x00 /* used internally */
SysName: pString "foo bar " /* System filename */
ShellName: pString "foo bar " /* Finder filename */
Dbg1Name: pString "foo bar " /* debugger filename */
Dbg2Name: pString "foo bar " /* debugger filename */
ScreenName: pString "foo bar " /* name of startup screen */
HelloName: pString "foo bar " /* name of startup program */
ScrapName: pString "foo bar " /* name of system scrap file */
CntFCBs: .short 10 /* number of FCBs to allocate */
CntEvts: .short 20 /* number of event queue elements */
Heap128K: .long 0x00004300 /* system heap size on 128K Mac */
Heap256K: .long 0x00008000 /* used internally */
SysHeapSize: .long 0x00020000 /* system heap size on all machines */
start:
/* Now running your code with full privs, what more do you want? ;) */
movel #0xDEAD, %d0 /* Error code for the Sad Mac screen */
.short 0xA9C9 /* Call the SysError trap */
end:
.fill stage1_size - (end - begin), 1, 0xda
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment