path: root/baremetal/boot.hex

# Code for the first few disk sectors that all programs in this directory need:
#   - load sectors past the first (using BIOS primitives) since only the first is available by default
#     - if this fails, print 'D' at top-left of screen and halt
#   - initialize a minimal graphics mode
#   - switch to 32-bit mode (giving up access to BIOS primitives)
#   - set up a handler for keyboard events
#   - jump to start of program
#
# To convert to a disk image, first prepare a realistically sized disk image:
#   dd if=/dev/zero of=disk.img count=20160  # 512-byte sectors, so 10MB
# Create initial sectors from this file:
#   ./bootstrap run apps/hex < baremetal/boot.hex > boot.bin
# Translate other sectors into a file called a.img
# Load all sectors into the disk image:
#   cat boot.bin a.img > disk.bin
#   dd if=disk.bin of=disk.img conv=notrunc
# To run:
#   qemu-system-i386 disk.img
# Or:
#   bochs -f baremetal/boot.bochsrc  # boot.bochsrc loads disk.img
#
# Since we start out in 16-bit mode, we need instructions SubX doesn't
# support.
# This file contains just lowercase hex bytes and comments. Programming it
# requires liberal use of:
#   - comments documenting expected offsets
#   - size checks on the emitted file (currently: 6144 bytes)
#   - xxd to spot-check contents of specific offsets in the generated output
#
# Programs using this initialization:
#   - can't use any syscalls
#   - 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) needs to know just
# a few magic constants:
#   Video memory: start is stored at 0x8128
#   Keyboard buffer: starts at 0x8028
#
# No mouse support. _That_ would require panicking.

# Outline of this file with offsets and the addresses they map to at run-time:
# -- 16-bit mode code
#   offset    0 (address 7c00): boot code
# -- 16-bit mode data
#            e0 (address 7c80) global descriptor table
#            f8 (address 7ca0) <== gdt_descriptor
# -- 32-bit mode code
#   offset  100 (address 7d00): boot code
#           1fe (address 7dfe) boot sector marker (2 bytes)
#   offset  200 (address 7e00): interrupt handler code
# -- 32-bit mode data
#   offset  400 (address 8000): handler data
#           410 (address 8010): keyboard handler data
#           428 (address 8028) <== keyboard buffer
#   offset  500 (address 8100): video mode data (256 bytes)
#           528 (address 8128) <== start of video RAM stored here
#   offset  600 (address 8200): interrupt descriptor table (1KB)
#   offset  a00 (address 8600): keyboard mappings (1.5KB)
#   offset 1000 (address 8c00): bitmap font (2KB)
#   offset 1800 (address 9400): entrypoint for applications (don't forget to adjust survey_baremetal if this changes)

# Other details of the current memory map:
#   code: first two default-sized disk tracks get loaded to [0x00007c00, 0x00017800)
#   stack grows down from 0x00070000
#     see below
#   heap: [0x01000000, 0x02000000)
#     see baremetal/120allocate.subx
# Consult https://wiki.osdev.org/Memory_Map_(x86) before modifying any of this.

## 16-bit entry point

# Upon reset, the IBM PC:
#   - loads the first sector (512 bytes)
#     from some bootable image (see the boot sector marker at the end of this file)
#     to the address range [0x7c00, 0x7e00)
#   - starts executing code at address 0x7c00

# offset 00 (address 0x7c00):
  # disable interrupts for this initialization
  fa  # cli

  # initialize segment registers
  # this isn't always needed, but the recommendation is to not make assumptions
  b8 00 00  # ax <- 0
  8e d8  # ds <- ax
  8e c0  # es <- ax
  8e e0  # fs <- ax
  8e e8  # gs <- ax

  # initialize stack to 0x00070000
  # We don't read or write the stack before we get to 32-bit mode, but BIOS
  # calls do. We need to move the stack in case BIOS initializes it to some
  # low address that we want to write code into.
  b8 00 70  # ax <- 0x7000
  8e d0  # ss <- ax
  bc 00 00  # sp <- 0x0000

# 14:
  # load remaining sectors from first two tracks of disk into addresses [0x7e00, 0x17800)
  b4 02  # ah <- 2  # read sectors from disk
  # dl comes conveniently initialized at boot time with the index of the device being booted
  b5 00  # ch <- 0  # cylinder 0
  b6 00  # dh <- 0  # track 0
  b1 02  # cl <- 2  # second sector, 1-based
  b0 7d  # al <- 125  # number of sectors to read
  # address to write sectors to = es:bx = 0x7e00, contiguous with boot segment
  bb 00 00  # bx <- 0
  8e c3  # es <- bx
  bb 00 7e  # bx <- 0x7e00 [label]
  cd 13  # int 13h, BIOS disk service
  0f 82 a3 00  # jump-if-carry disk_error [label]

# 2c:
  # undo the A20 hack: https://en.wikipedia.org/wiki/A20_line
  # this is from https://github.com/mit-pdos/xv6-public/blob/master/bootasm.S
  # seta20.1:
  e4 64  # al <- port 0x64
  a8 02  # set zf if bit 1 (second-least significant) is not set
  75 fa  # if zf not set, goto seta20.1 (-6)

  b0 d1  # al <- 0xd1
  e6 64  # port 0x64 <- al

# 36:
  # seta20.2:
  e4 64  # al <- port 0x64
  a8 02  # set zf if bit 1 (second-least significant) is not set
  75 fa  # if zf not set, goto seta20.2 (-6)

  b0 df  # al <- 0xdf
  e6 64  # port 0x64 <- al

# 40:
  # adjust video mode
  b4 4f  # ah <- 4f (VBE)
  b0 02  # al <- 02 (set video mode)
  bb 05 41  # bx <- 0x0105 (graphics 1024x768x256
            #               0x4000 bit = configure linear frame buffer in Bochs emulator; hopefully this doesn't hurt anything when running natively)
            # fallback mode: 0x0101 (640x480x256)
  cd 10  # int 10h, Vesa BIOS extensions

# 49:
  # load information for the (hopefully) current video mode
  # mostly just for the address to the linear frame buffer
  b4 4f  # ah <- 4f (VBE)
  b0 01  # al <- 01 (get video mode info)
  b9 07 01  # cx <- 0x0107 (mode we requested)
  bf 00 81  # di <- 0x8100 (video mode info) [label]
  cd 10

# 55:
  # switch to 32-bit mode
  0f 01 16  # lgdt 00/mod/indirect 010/subop 110/rm/use-disp16
    f8 7c  # *gdt_descriptor [label]
  0f 20 c0  # eax <- cr0
  66 83 c8 01  # eax <- or 0x1
  0f 22 c0  # cr0 <- eax
  ea 00 7d 08 00  # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) [label]

# padding
# 69:
                           00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# cf:
# disk_error:
  # print 'D' to top-left of screen to indicate disk error
  # *0xb8000 <- 0x0f44
  # bx <- 0xb800
  bb 00 b8
  # ds <- bx
  8e db  # 11b/mod 011b/reg/ds 011b/rm/bx
  # al <- 'D'
  b0 44
  # ah <- 0x0f  # white on black
  b4 0f
  # bx <- 0
  bb 00 00
  # *ds:bx <- ax
  89 07  # 00b/mod/indirect 000b/reg/ax 111b/rm/bx

e9 fd ff  # loop forever

## GDT: 3 records of 8 bytes each

# e0:
# gdt_start:
# gdt_null:  mandatory null descriptor
  00 00 00 00 00 00 00 00
# gdt_code:  (offset 8 from gdt_start)
  ff ff  # limit[0:16]
  00 00 00  # base[0:24]
  9a  # 1/present 00/privilege 1/descriptor type = 1001b
      # 1/code 0/conforming 1/readable 0/accessed = 1010b
  cf  # 1/granularity 1/32-bit 0/64-bit-segment 0/AVL = 1100b
      # limit[16:20] = 1111b
  00  # base[24:32]
# gdt_data:  (offset 16 from gdt_start)
  ff ff  # limit[0:16]
  00 00 00  # base[0:24]
  92  # 1/present 00/privilege 1/descriptor type = 1001b
      # 0/data 0/conforming 1/readable 0/accessed = 0010b
  cf  # same as gdt_code
  00  # base[24:32]
# gdt_end:

# f8:
# gdt_descriptor:
  17 00  # final index of gdt = gdt_end - gdt_start - 1
  e0 7c 00 00  # start = gdt_start [label]

# padding
# fe:
                                          00 00

## 32-bit code from this point (still some instructions not in SubX)

# offset 100 (address 0x7d00):
# initialize_32bit_mode:
  66 b8 10 00  # ax <- offset 16 from gdt_start
  8e d8  # ds <- ax
  8e d0  # ss <- ax
  8e c0  # es <- ax
  8e e0  # fs <- ax
  8e e8  # gs <- ax

# 10e:
  bc 00 00 07 00  # esp <- 0x00070000

# 113:
  # load interrupt handlers
  0f 01 1d  # lidt 00/mod/indirect 011/subop 101/rm32/use-disp32
    00 80 00 00  # *idt_descriptor [label]

  # For now, not bothering reprogramming the IRQ to not conflict with software
  # exceptions.
  #   https://wiki.osdev.org/index.php?title=8259_PIC&oldid=24650#Protected_Mode
  #
  # Interrupt 1 (keyboard) conflicts with debugger faults. We don't use a
  # debugger.
  # Reference:
  #   https://wiki.osdev.org/Exceptions

# 11a:
  # enable keyboard IRQ (1)
  b0 fd  # al <- 0xfd  # disable mask for IRQ1
  e6 21  # port 0x21 <- al

# 11e:
  fb  # enable interrupts
  db e3  # initialize FPU
  # eax <- cr4
  0f 20  # copy cr4 to rm32
    e0  # 11/mod/direct 100/r32/CR4 000/rm32/eax
  # eax <- or bit 9
  0f ba
    e8  # 11/mod/direct 101/subop/bit-test-and-set 000/rm32/eax
    09  # imm8
  # cr4 <- eax
  0f 22  # copy rm32 to cr4
    e0  # 11/mod/direct 100/r32/CR4 000/rm32/eax
  e9 d0 16 00 00  # jump to 0x9400 [label]

# padding
# 130:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00

# 1fe:
# final 2 bytes of boot sector
55 aa

## sector 2 onwards loaded by load_disk, not automatically on boot

# offset 200 (address 0x7e00):
# null interrupt handler:
  cf  # iret

# padding
# 201:
   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# 210:
# keyboard interrupt handler:
  # prologue
  fa  # disable interrupts
  60  # push all registers to stack
  # acknowledge interrupt
  b0 20  # al <- 0x20
  e6 20  # port 0x20 <- al
  31 c0  # eax <- xor eax;  11/direct 000/r32/eax 000/rm32/eax
  # check output buffer of 8042 keyboard controller (https://web.archive.org/web/20040604041507/http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/keyboard/atkeyboard.html)
  e4 64  # al <- port 0x64
  a8 01  # set zf if bit 0 (least significant) is not set
  74 89  # jump to epilogue if 0 bit is not set [label]
# 21e:
  # - if keyboard buffer is full, return
  31 c9  # ecx <- xor ecx;  11/direct 001/r32/ecx 001/rm32/ecx
  # var index/ecx: byte
  8a  # copy m8 at r32 to r8
    0d  # 00/mod/indirect 001/r8/cl 101/rm32/use-disp32
    28 80 00 00  # disp32 [label]
  # al = *(keyboard buffer + index)
  8a  # copy m8 at r32 to r8
    81  # 10/mod/*+disp32 000/r8/al 001/rm32/ecx
    30 80 00 00  # disp32 [label]
  # if (al != 0) return
  3c 00  # compare al, 0
  75 77  # jump to epilogue if != [label]
# 230:
  # - read keycode
  e4 60  # al <- port 0x60
  # - key released
  # if (al == 0xaa) shift = false  # left shift is being lifted
  3c aa  # compare al, 0xaa
  75 0a  # jump to $1 if != [label]
  # *shift = 0
  c7  # copy imm32 to rm32
    05  # 00/mod/indirect 000/subop/copy 101/rm32/use-disp32
    10 80 00 00  # disp32 [label]
    00 00 00 00  # imm32
# 240:
# $1:
  # if (al == 0xb6) shift = false  # right shift is being lifted
  3c b6  # compare al, 0xb6
  75 0a  # jump to $1 if != [label]
  # *shift = 0
  c7  # copy imm32 to rm32
    05  # 00/mod/indirect 000/subop/copy 101/rm32/use-disp32
    10 80 00 00  # disp32 [label]
    00 00 00 00  # imm32
# $2:
  # if (al & 0x80) a key is being lifted; return
  50  # push eax
  24 80  # al <- and 0x80
  3c 00  # compare al, 0
  58  # pop to eax (without touching flags)
  75 51  # jump to epilogue if != [label]
# 256:
  # - key pressed
  # if (al == 0x2a) shift = true, return  # left shift pressed
  3c 2a  # compare al, 0x2a
  75 0c  # jump to $3 if != [label]
  # *shift = 1
  c7  # copy imm32 to rm32
    05  # 00/mod/indirect 000/subop/copy 101/rm32/use-disp32
    10 80 00 00  # disp32 [label]
    01 00 00 00  # imm32
  eb 41 # jump to epilogue [label]
# 266:
# $3:
  # if (al == 0x36) shift = true, return  # right shift pressed
  3c 36  # compare al, 0x36
  75 0c  # jump to $4 if != [label]
  # *shift = 1
  c7  # copy imm32 to rm32
    05  # 00/mod/indirect 000/subop/copy 101/rm32/use-disp32
    10 80 00 00  # disp32 [label]
    01 00 00 00  # imm32
  eb 31 # jump to epilogue [label]
# 276:
# $4:
  # - convert key to character
  # if (shift) use keyboard normal map
  81  # operate on rm32 and imm32
    3d  # 00/mod/indirect 111/subop/compare 101/rm32/use-disp32
    10 80 00 00  # disp32 = shift [label]
    00 00 00 00  # imm32
  74 08  # jump to $5 if = [label]
  # otherwise use keyboard shift map
  # al <- *(keyboard shift map + eax)
  8a  # copy m8 at rm32 to r8
    80  # 10/mod/*+disp32 000/r8/al 000/rm32/eax
    00 87 00 00  # disp32 [label]
  eb 06  # jump to $6 [label]
# 28a:
# $5:
  # al <- *(keyboard normal map + eax)
  8a  # copy m8 at rm32 to r8
    80  # 10/mod/*+disp32 000/r8/al 000/rm32/eax
    00 86 00 00  # disp32 [label]
# $6:
  # - if there's no character mapping, return
  3c 00  # compare al, 0
  74 13  # jump to epilogue if = [label]
# 294:
  # - store al in keyboard buffer
  88  # copy r8 to m8 at r32
    81  # 10/mod/*+disp32 000/r8/al 001/rm32/ecx
    30 80 00 00  # disp32 [label]
  # increment index
  fe  # increment byte
    05  # 00/mod/indirect 000/subop/increment 101/rm32/use-disp32
    28 80 00 00  # disp32 [label]
  # clear top nibble of index (keyboard buffer is circular)
  80  # and byte
    25  # 00/mod/indirect 100/subop/and 101/rm32/use-disp32
    28 80 00 00  # disp32 [label]
    0f  # imm8
# 2a9:
  # epilogue
  61  # pop all registers
  fb  # enable interrupts
  cf  # iret

# padding
# 2aa:
                              00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# 300:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# offset 400 (address 0x8000): interrupt handler data
# idt_descriptor:
  ff 03  # idt_end - idt_start - 1
  00 82 00 00  # start = idt_start [label]

# padding
# 406:
                  00 00 00 00 00 00 00 00 00 00

# 410:
# var shift: boolean
  00 00 00 00

# padding
# 414:
            00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 428:
# var keyboard circular buffer
# write index: nibble
# still take up 4 bytes so SubX can handle it
  00 00 00 00
# 42c:
# read index: nibble
# still take up 4 bytes so SubX can handle it
  00 00 00 00
# 430:
# circular buffer: byte[16]
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# padding
# 440:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# offset 500 (address 0x8100):
# video mode info {{{
  00 00  # attributes
  00  # winA
  00  # winB
# 04
  00 00  # granularity
  00 00  # winsize
# 08
  00 00  # segmentA
  00 00  # segmentB
# 0c
  00 00 00 00  # realFctPtr (who knows)
# 10
  00 00  # pitch
  00 00  # Xres
# 14
  00 00  # Yres
  00 00  # Wchar Ychar
# 18
  00  # planes
  00  # bpp
  00  # banks
  00  # memory_model
# 1c
  00  # bank_size
  00  # image_pages
  00  # reserved
# 1f
  00 00  # red_mask red_position
  00 00  # green_mask green_position
  00 00  # blue_mask blue_position
  00 00  # rsv_mask rsv_position
  00  # directcolor_attributes
# 28
  00 00 00 00  # physbase <== linear frame buffer

# 2c
# reserved for video mode info
                                    00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# }}}

# offset 600 (address 0x8200):
# interrupt descriptor table {{{
# 128 entries * 8 bytes each = 1024 bytes (0x400)
# idt_start:

# entry 0
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# By default, BIOS maps IRQ0-7 to interrupt vectors 8-15.
# https://wiki.osdev.org/index.php?title=Interrupts&oldid=25102#Default_PC_Interrupt_Vector_Assignment

# entry 8: clock
  00 7e  # target[0:16] = null interrupt handler [label]
  08 00  # segment selector (gdt_code)
  00  # unused
  8e  # 1/p 00/dpl 0 1110/type/32-bit-interrupt-gate
  00 00  # target[16:32]

# entry 9: keyboard
  10 7e  # target[0:16] = keyboard interrupt handler [label]
  08 00  # segment selector (gdt_code)
  00  # unused
  8e  # 1/p 00/dpl 0 1110/type/32-bit-interrupt-gate
  00 00  # target[16:32]

00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 500:
# entry 0x20
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 600:
# entry 0x40
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 700:
# entry 0x60
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
# entry 0x70
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
# idt_end:
# }}}

## the rest of this file has data

# offset a00 (address 0x8600):
# translating keys to ASCII {{{
# keyboard normal map:
00
#  es
   1b
#     |<--- digits -------------->| -  =  backspace
      31 32 33 34 35 36 37 38 39 30 2d 3d 08
# 0f
# tab q  w  e  r  t  y  u  i  o  p  [  ]
   09 71 77 65 72 74 79 75 69 6f 70 5b 5d
# 1c
#                                         enter
                                          0a 00
# 1e
#     a  s  d  f  g  h  j  k  l  ;  '  `     \
      61 73 64 66 67 68 6a 6b 6c 3b 27 60 00 5c
                                        # ^ left shift
# 2c
#     z  x  c  v  b  n  m  ,  .  /     *
      7a 78 63 76 62 6e 6d 2c 2e 2f 00 2a
                                  # ^ right shift
# 38
#                          space
                        00 20
# 3a
                              00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# numeric keypad would start here, but isn't implemented
                                             00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# offset b00:
# keyboard shift map:
00
#  es
   1b
#     !  @  #  $  %  ^  &  *  (  )  _  +  backspace
      21 40 23 24 25 53 26 2a 28 29 5f 2b 08
# 0f
# tab Q  W  E  R  T  Y  U  I  O  P  {  }
   09 51 57 55 52 54 59 55 59 5f 50 7b 7d
# 1c
#                                         enter
                                          0a 00
# 1e
#     A  S  D  F  G  H  J  K  L  :  "  ~     |
      41 53 44 46 47 48 4a 4b 4c 3a 22 7e 00 7c
# 2c
#     Z  X  C  V  B  N  M  <  >  ?     *
      5a 58 43 56 42 4e 4d 3c 3e 3f 00 2a
# 38
#                          space
                        00 20
# 3a
                              00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# numeric keypad would start here, but isn't implemented
                                             00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# c00:
# keyboard ctrl map:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# padding (there might be more keyboard tables)
# d00:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# e00:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# f00:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# }}}

# offset 1000 (address 0x8c00)
# Bitmaps for some ASCII characters (soon Unicode) {{{
# Part of GNU Unifont
# 8px wide, 16px tall
# Based on http://unifoundry.com/pub/unifont/unifont-13.0.05/font-builds/unifont-13.0.05.hex.gz
# See https://en.wikipedia.org/wiki/GNU_Unifont#The_.hex_font_format
# Website: http://unifoundry.com/unifont/index.html
# License: http://unifoundry.com/LICENSE.txt (GPL v2)
# Each line below is a bitmap for a single character.
#   Each byte is a bitmap for a single row of 8 pixels.

# some unprintable ASCII chars
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# 0x20 = space
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# !
  00 00 00 00 08 08 08 08 08 08 08 00 08 08 00 00
# "
  00 00 22 22 22 22 00 00 00 00 00 00 00 00 00 00
# 0x23 = '#'
  00 00 00 00 12 12 12 7e 24 24 7e 48 48 48 00 00
# $
  00 00 00 00 08 3e 49 48 38 0e 09 49 3e 08 00 00
# %
  00 00 00 00 31 4a 4a 34 08 08 16 29 29 46 00 00
# &
  00 00 00 00 1c 22 22 14 18 29 45 42 46 39 00 00
# '
  00 00 08 08 08 08 00 00 00 00 00 00 00 00 00 00
# (
  00 00 00 04 08 08 10 10 10 10 10 10 08 08 04 00
# )
  00 00 00 20 10 10 08 08 08 08 08 08 10 10 20 00
# *
  00 00 00 00 00 00 08 49 2a 1c 2a 49 08 00 00 00
# +
  00 00 00 00 00 00 08 08 08 7f 08 08 08 00 00 00
# ,
  00 00 00 00 00 00 00 00 00 00 00 00 18 08 08 10
# -
  00 00 00 00 00 00 00 00 00 3c 00 00 00 00 00 00
# .
  00 00 00 00 00 00 00 00 00 00 00 00 18 18 00 00
# /
  00 00 00 00 02 02 04 08 08 10 10 20 40 40 00 00
# 0x30 = '0'
  00 00 00 00 18 24 42 46 4a 52 62 42 24 18 00 00
# 1
  00 00 00 00 08 18 28 08 08 08 08 08 08 3e 00 00
# 2
  00 00 00 00 3c 42 42 02 0c 10 20 40 40 7e 00 00
# 3
  00 00 00 00 3c 42 42 02 1c 02 02 42 42 3c 00 00
# 4
  00 00 00 00 04 0c 14 24 44 44 7e 04 04 04 00 00
# 5
  00 00 00 00 7e 40 40 40 7c 02 02 02 42 3c 00 00
# 6
  00 00 00 00 1c 20 40 40 7c 42 42 42 42 3c 00 00
# 7
  00 00 00 00 7e 02 02 04 04 04 08 08 08 08 00 00
# 8
  00 00 00 00 3c 42 42 42 3c 42 42 42 42 3c 00 00
# 9
  00 00 00 00 3c 42 42 42 3e 02 02 02 04 38 00 00
# :
  00 00 00 00 00 00 18 18 00 00 00 18 18 00 00 00
# ;
  00 00 00 00 00 00 18 18 00 00 00 18 08 08 10 00
# <
  00 00 00 00 00 02 04 08 10 20 10 08 04 02 00 00
# =
  00 00 00 00 00 00 00 7e 00 00 00 7e 00 00 00 00
# >
  00 00 00 00 00 40 20 10 08 04 08 10 20 40 00 00
# ?
  00 00 00 00 3c 42 42 02 04 08 08 00 08 08 00 00
# 0x40 = @
  00 00 00 00 1c 22 4a 56 52 52 52 4e 20 1e 00 00
# A
  00 00 00 00 18 24 24 42 42 7e 42 42 42 42 00 00
# B
  00 00 00 00 7c 42 42 42 7c 42 42 42 42 7c 00 00
# C
  00 00 00 00 3c 42 42 40 40 40 40 42 42 3c 00 00
# D
  00 00 00 00 78 44 42 42 42 42 42 42 44 78 00 00
# E
  00 00 00 00 7e 40 40 40 7c 40 40 40 40 7e 00 00
# F
  00 00 00 00 7e 40 40 40 7c 40 40 40 40 40 00 00
# G
  00 00 00 00 3c 42 42 40 40 4e 42 42 46 3a 00 00
# H
  00 00 00 00 42 42 42 42 7e 42 42 42 42 42 00 00
# I
  00 00 00 00 3e 08 08 08 08 08 08 08 08 3e 00 00
# J
  00 00 00 00 1f 04 04 04 04 04 04 44 44 38 00 00
# K
  00 00 00 00 42 44 48 50 60 60 50 48 44 42 00 00
# L
  00 00 00 00 40 40 40 40 40 40 40 40 40 7e 00 00
# M
  00 00 00 00 42 42 66 66 5a 5a 42 42 42 42 00 00
# N
  00 00 00 00 42 62 62 52 52 4a 4a 46 46 42 00 00
# O
  00 00 00 00 3c 42 42 42 42 42 42 42 42 3c 00 00
# 0x50 = P
  00 00 00 00 7c 42 42 42 7c 40 40 40 40 40 00 00
# Q
  00 00 00 00 3c 42 42 42 42 42 42 5a 66 3c 03 00
# R
  00 00 00 00 7c 42 42 42 7c 48 44 44 42 42 00 00
# S
  00 00 00 00 3c 42 42 40 30 0c 02 42 42 3c 00 00
# T
  00 00 00 00 7f 08 08 08 08 08 08 08 08 08 00 00
# U
  00 00 00 00 42 42 42 42 42 42 42 42 42 3c 00 00
# V
  00 00 00 00 41 41 41 22 22 22 14 14 08 08 00 00
# W
  00 00 00 00 42 42 42 42 5a 5a 66 66 42 42 00 00
# X
  00 00 00 00 42 42 24 24 18 18 24 24 42 42 00 00
# Y
  00 00 00 00 41 41 22 22 14 08 08 08 08 08 00 00
# Z
  00 00 00 00 7e 02 02 04 08 10 20 40 40 7e 00 00
# [
  00 00 00 0e 08 08 08 08 08 08 08 08 08 08 0e 00
# \
  00 00 00 00 40 40 20 10 10 08 08 04 02 02 00 00
# ]
  00 00 00 70 10 10 10 10 10 10 10 10 10 10 70 00
# ^
  00 00 18 24 42 00 00 00 00 00 00 00 00 00 00 00
# _
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 7f 00
# 0x60 = backtick
  00 20 10 08 00 00 00 00 00 00 00 00 00 00 00 00
# a
  00 00 00 00 00 00 3c 42 02 3e 42 42 46 3a 00 00
# b
  00 00 00 40 40 40 5c 62 42 42 42 42 62 5c 00 00
# c
  00 00 00 00 00 00 3c 42 40 40 40 40 42 3c 00 00
# d
  00 00 00 02 02 02 3a 46 42 42 42 42 46 3a 00 00
# e
  00 00 00 00 00 00 3c 42 42 7e 40 40 42 3c 00 00
# f
  00 00 00 0c 10 10 10 7c 10 10 10 10 10 10 00 00
# g
  00 00 00 00 00 02 3a 44 44 44 38 20 3c 42 42 3c
# h
  00 00 00 40 40 40 5c 62 42 42 42 42 42 42 00 00
# i
  00 00 00 08 08 00 18 08 08 08 08 08 08 3e 00 00
# j
  00 00 00 04 04 00 0c 04 04 04 04 04 04 04 48 30
# k
  00 00 00 40 40 40 44 48 50 60 50 48 44 42 00 00
# l
  00 00 00 18 08 08 08 08 08 08 08 08 08 3e 00 00
# m
  00 00 00 00 00 00 76 49 49 49 49 49 49 49 00 00
# n
  00 00 00 00 00 00 5c 62 42 42 42 42 42 42 00 00
# o
  00 00 00 00 00 00 3c 42 42 42 42 42 42 3c 00 00
# 0x70 = p
  00 00 00 00 00 00 5c 62 42 42 42 42 62 5c 40 40
# q
  00 00 00 00 00 00 3a 46 42 42 42 42 46 3a 02 02
# r
  00 00 00 00 00 00 5c 62 42 40 40 40 40 40 00 00
# s
  00 00 00 00 00 00 3c 42 40 30 0c 02 42 3c 00 00
# t
  00 00 00 00 10 10 10 7c 10 10 10 10 10 0c 00 00
# u
  00 00 00 00 00 00 42 42 42 42 42 42 46 3a 00 00
# v
  00 00 00 00 00 00 42 42 42 24 24 24 18 18 00 00
# w
  00 00 00 00 00 00 41 49 49 49 49 49 49 36 00 00
# x
  00 00 00 00 00 00 42 42 24 18 18 24 42 42 00 00
# y
  00 00 00 00 00 00 42 42 42 42 42 26 1a 02 02 3c
# z
  00 00 00 00 00 00 7e 02 04 08 10 20 40 7e 00 00
# {
  00 00 00 0c 10 10 08 08 10 20 10 08 08 10 10 0c
# |
  00 00 08 08 08 08 08 08 08 08 08 08 08 08 08 08
# }
  00 00 00 30 08 08 10 10 08 04 08 10 10 08 08 30
# ~
  00 00 00 31 49 46 00 00 00 00 00 00 00 00 00 00
# 0x7f = del (unused)
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# }}}

# offset 1800 (address 0x9400)

# vim:ft=subx