Hexheld ROM Format.txt

HiveCraft Memory Map:

$000000 - $007FFF   32 KB    WRAM
$008000 - $00FFFF   32 KB    VRAM
$010000 - $0FFFFF   ~1 MB    Hexridge CS1 (first 64 KB inaccessible)
$100000 - $1FFFFF    1 MB    Hexridge CS2
$200000 - $FF9FFF  ~14 MB    Hexridge ROM
$FFA000 - $FFDFFF   16 KB    Boot ROM ->(unmap)-> Hexridge ROM
$FFE000 - $FFEFFF    4 KB    Tilemap RAM
$FFF000 - $FFF27F   640 B    Sprite Attribute RAM
$FFF280 - $FFF3FF            I/O Registers
$FFF400 - $FFFFFF    3 KB    HRAM

Hexridge ROM Organization:

$..0000 - $FF9EFF    General Purpose
$FF9F00 - $FF9FFF    ROM Header
$FFA000 - $FFCEFF    General Purpose
$FFCF00 - $FFCFFF    Interrupt and Exception Vectors
                   $FFCFF0 == Entry Point == Reset Vector
$FFD000 - $FFDFFF    RST Code Area
$FFE000 - $FFFFFF    <inaccessible>

ROM Header:

+$00 - +$7F      Game title     (ASCII, null-terminated, 127 characters maximum)
+$80 - +$DF      Game developer (ASCII, null-terminated, 95 characters maximum)
+$E0 - +$EF    * Magic "HEXHELD SOFTWARE" (ASCII)
+$F0             ROM size in 64 KB units (e.g. $10 for a 1 MB ROM)
+$F1             CS1 chip type
+$F2             CS2 chip type
+$F3           * Minimum SoC version number
+$F4 - +$F7      <$00 filling>
+$F8 - +$F9      Software revision number (16-bit, starts at 1)
+$FA - +$FB      Copyright inclusive start year (4-digit BCD)
+$FC - +$FD      Copyright inclusive end year   (4-digit BCD)
+$FE - +$FF    * CRC-16 (polynomial $D175) of above 254 bytes (+$00 - +$FD)

* These fields are validated by the boot ROM program.