header.txt

Super UFO copier header format
by Revenant

last updated 2018/07/19

0000 1 byte  ROM size in megabits (4, 8, 10, 12, 16, 24, 32)
0001 1 byte  unused
0002 1 byte  ROM mapping (1 = lorom, 0 = hirom)
0003 5 bytes unused
0008 8 bytes "SFCUFOSD"

0010 1 byte  unused
0011 1 byte  ROM size in megabits (rounded up to power of 2)
0012 1 byte  SRAM present
	00 = none
	01 = 16kbit (2kb)
	02 = 64kbit (8kb)
	03 = 256kbit (32kb)
	07 = 1Mbit (128kb)
	(written to bits 0-2 of $2184)

0013 2 bytes ROM mapping
	A23:A16 DRAM mapping and address translation
	(written to $2186-87)
	
	examples:
LoROM 4M = 05 2a (x0-x7:8000-ffff, x8-xf:8000-ffff)
      8M = 15 28 (x0-xf:8000-ffff)
 10..16M = 55 20 (00-1f:8000-ffff, 20-3f, 80-9f,...)
 24..32M = 55 00 (00-3f:8000-ffff, 80-bf...)
HiROM 4M = 09 00 (40-43:0000-ffff, c0-c3, c4-c7...)
      8M = 25 00 (40-47:0000-ffff, c0-c7, c8-cf...)
     10M = 37 00
     12M = 3d 00
     16M = 95 00 (40-4f:0000-ffff, c0-cf...)
     24M = f5 00
     32M = 55 00 (40-5f:0000-ffff, c0-df...)

0015 1 byte  SRAM A15
	00 = 0 (HiROM)  (xx:6000-7fff)
	10 = don't care (xx:0000-ffff)
	20 = 0 (LoROM)  (xx:0000-7fff) if more than 2MB ROM or 32kb SRAM
	30 = 1          (xx:8000-ffff)
	possibly ORed with either of...
	40 = 24-32Mbit LoROM
	80 = 32Mbit HiROM
	(written to bits 4-7 of $2184)
	
0016 1 byte  SRAM A23:20 (2 bits each, A23 most significant)
	00b = don't care
	01b = don't care (not used by firmware)
	10b = 0
	11b = 1
	(written to $2185)
	
	default for LoROM : 3f (7x, fx = x111xxxxb = 00111111b)
	default for HiROM : 2c (2x-3x, ax-bx = x01xxxxxb = 00101100b)

0017 1 byte  ROM mapping (same as 0002, written to $218f)
0018 1 byte  region (00 = NTSC, 02 = PAL)
0019 1 byte  expansion chip (00 = no, FF = yes)
001A 6 bytes unused

0020 32 bytes copy of cartridge header (00FFC0-00FFDF)