path: root/baremetal/boot.hex

# Code for the first disk sector 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. Zero
# error-checking. Make liberal use of:
#   - comments documenting expected offsets
#   - size checks on the emitted file (currently: 512 bytes)
#   - xxd to eyeball that offsets contain expected bytes
#
# 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 store their entry-point at address 0x9000

## 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 d0  # ss <- ax
  8e c0  # es <- ax
  8e e0  # fs <- ax
  8e e8  # gs <- ax

  # We don't read or write the stack before we get to 32-bit mode. No function
  # calls, so we don't need to initialize the stack.

# 0e:
  # load some sectors from disk
  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 80  # al <- 128  # number of sectors to read; TODO - all sectors might need to be in a single track on real hardware (so 63 sectors at most including the boot sector)
  # 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 8a 00  # jump-if-carry disk-error [label]

# 26:
  # 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

# 30:
  # 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

# 3a:
  # 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

# 43:
  # 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)
  b9 07 01  # cx <- 0x0107 (mode we requested)
  bf 00 7f  # di <- 0x7f00 (video mode info) [label]
  cd 10

# 4f:
  # switch to 32-bit mode
  0f 01 16  # lgdt 00/mod/indirect 010/subop 110/rm/use-disp16
    a0 7c  # *gdt_descriptor [label]
  0f 20 c0  # eax <- cr0
  66 83 c8 01  # eax <- or 0x1
  0f 22 c0  # cr0 <- eax
  ea e0 7c 08 00  # far jump to initialize_32bit_mode after setting cs to the record at offset 8 in the gdt (gdt_code) [label]

# padding
# 63:
         00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

## GDT: 3 records of 8 bytes each

# 80:
# 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:

# padding
# 98:
                        00 00 00 00 00 00 00 00

# a0:
# gdt_descriptor:
  17 00  # final index of gdt = gdt_end - gdt_start - 1
  80 7c 00 00  # start = gdt_start [label]

# padding
# a5:
                  00 00 00 00 00 00 00 00 00 00

# b0:
# 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 fb ff  # loop forever

# padding
# c1:
   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

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

# e0:
# 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

  # load interrupt handlers
  0f 01 1d  # lidt 00/mod/indirect 011/subop 101/rm32/use-disp32
    f8 7d 00 00  # *idt_descriptor [label]

  # enable keyboard IRQ
  b0 fd  # al <- 0xfd  # enable just IRQ1
  e6 21  # port 0x21 <- al

  # initialization is done; enable interrupts
  fb
  e9 01 13 00 00  # jump to 0x9000 [label]

# padding
# ff:
                                             00

# 100:
# null interrupt handler:
  cf  # iret

# padding
# 101:
   00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# 110:
# keyboard interrupt handler:
  # prologue
  fa  # disable interrupts
  60  # push all registers to stack
  # acknowledge interrupt
  b0 20  # al <- 0x20
  e6 20  # port 0x20 <- al
  # read status into eax
  31 c0  # eax <- xor eax;  11/direct 000/r32/eax 000/rm32/eax
  e4 64  # al <- port 0x64
  # if (status & 0x1) == 0, return
  24 01  # al <- and 0x1
  3c 00  # compare al, 0
  74 39  # jump to epilogue if = [label]
# 120:
  # 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
    c8 7d 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
    d0 7d 00 00  # disp32 [label]
  # . if (al != 0) return
  3c 00  # compare al, 0
# 130:
  75 27  # jump to epilogue if != [label]
  # read keycode into al
  e4 60  # al <- port 0x60
  # 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 1d  # jump to epilogue if != [label]
# 13c:
  # al <- *(keyboard normal map + eax)
  8a  # copy m8 at rm32 to r8
    80  # 10/mod/*+disp32 000/r8/al 000/rm32/eax
    00 80 00 00  # disp32 [label]
  # if there's no character mapping, return
  3c 00  # compare al, 0
  74 13  # jump to epilogue if = [label]
# 146:
  # store al in keyboard buffer
  88  # copy r8 to m8 at r32
    81  # 10/mod/*+disp32 000/r8/al 001/rm32/ecx
    d0 7d 00 00  # disp32 [label]
# 14c:
  # increment index
  fe  # increment byte
    05  # 00/mod/indirect 000/subop/increment 101/rm32/use-disp32
    c8 7d 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
    c8 7d 00 00  # disp32 [label]
    0f  # imm8
# 159:
  # epilogue
  61  # pop all registers
  fb  # enable interrupts
  cf  # iret

# padding
# 15c:
                                    00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 1c8:
# var keyboard circular buffer
# write index: nibble
# still take up 4 bytes so SubX can handle it
  00 00 00 00
# 1cc:
# read index: nibble
# still take up 4 bytes so SubX can handle it
  00 00 00 00
# 1d0:
# circular buffer: byte[16]
  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# padding
# 1e0:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00

# 1f8:
# idt_descriptor:
  ff 00  # idt_end - idt_start - 1
  00 7e 00 00  # start = idt_start [label]

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

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

# offset 200 (address 0x7e00): interrupt descriptor table
# 32 entries * 8 bytes each = 256 bytes (0x100)
# idt_start:

00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
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 8: clock
  00 7d  # 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 7d  # 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
# idt_end:

# offset 300 (address 0x7f00):
# video mode info:
  00 00  # attributes
  00  # winA
  00  # winB
# 304
  00 00  # granularity
  00 00  # winsize
# 308
  00 00  # segmentA
  00 00  # segmentB
# 30c
  00 00 00 00  # realFctPtr (who knows)
# 310
  00 00  # pitch
  00 00  # Xres
# 314
  00 00  # Yres
  00 00  # Wchar Ychar
# 318
  00  # planes
  00  # bpp
  00  # banks
  00  # memory_model
# 31c
  00  # bank_size
  00  # image_pages
  00  # reserved
# 31f
  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
# 328
  00 00 00 00  # physbase <== linear frame buffer

# 32c
# 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

## the rest of this file has data

# offset 400 (address 0x8000):
# translating keys to ASCII {{{
# keyboard normal map:
00
#  es
   1b
#     |<--- digits -------------->| -  =  bs
      31 32 33 34 35 36 37 38 39 30 2d 3d 08
# offset 40f
#  tb q  w  e  r  t  y  u  i  o  p  [  ]
   09 71 77 65 72 74 79 75 69 6f 70 5b 5d
# offset 41c
#                                         enter
                                          0a 00
# offset 41e
#     a  s  d  f  g  h  j  k  l  ;  '  `     \
      61 73 64 66 67 68 6a 6b 6c 3b 27 60 00 5c
# offset 42c
#     z  x  c  v  b  n  m  ,  .  /     *
      7a 78 63 76 62 6e 6d 2c 2e 2f 00 2a
# offset 438
#                          space
                        00 20
# offset 43a
                              00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 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:
# keyboard shift 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

# 600:
# 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)
# 700:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# 800:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
# a00:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 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 c00 (address 0x8800)
# 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 1400 (address 0x9000)

# vim:ft=subx