BS-X BIOS Functions

All those documented BIOS functions are based from the SRAM Map; In case of an updated version, I'll put it with the original.

Function names are based on nocash's doc:

1059A4 init_port_2199_registers


  JML $80C36D //init_port_2199_registers


SuperDisc Memory Map

Documentation based on byuu's findings.

Super Disc System Cartridge

$00-7D:8000-FFFF: BIOS ROM
$80-87:8000-FFFF: Expansion RAM (128KiB)
$90   :8000-9FFF: CMOS Backup RAM (8KiB)


Satellaview Download Data

Super Famicom Channel Map (Hardware Channel $0124)

Download Header

(Goes to $7E9A34)
$00-$01 : Unused.
$02 : Unknown (Copies to RAM $1411)
$03-$04 : 16-bit Big Endian Data Size (Copies to RAM $140F in Little Endian)

Channel Map Header

(Goes to $ ...

Game Doctor

Bung Game Doctor SF3, SF6, SF7 Headers

Version 1.0 - Copyright 2003: The Dumper

The Game Doctor SF3/SF6/SF7 backup units for the SNES use a 512 byte header.

The format is as follows (all numbers are hexadecimal):


`47 41 4D 45 20 44 4F 43 54 4F 52 20 53 46 20 33 ...

Super Wild Card

Hardware Specification to SWC & SMC Programmer Only

  1. DRAM - 28 Mega Bits Maximum Available.
  2. SRAM - 256K Bits. (Battery Backup)
  3. ROM - 128K Bits. (Firmware)
  4. Floppy Drive Interface
  • Motorola MCS3201 Chip. (NEC 765a Compatible)
  • Compatible With IBM PC/at and XT Disk Drive Syst ...



The SNES has 2 controller ports on the front of the unit, and an "expansion port" on the bottom. Little is known about the expansion port.

A number of peripherals could be plugged into the controller ports:


The BS-X cartridge has a MMIO included in Memory 00-0f:5000. (Info taken from bsnes and sd2snes' verilog source)

They all do different things to the Memory, and is NECESSARY, to run games, and other stuff.

We will call them from r00 to r0f. Those have only one bit that can be set.

MCC ...

BS-X Satellaview Header

The header will be at 0x7xxx (for LoROM) or 0xFxxx (for HiROM) for the downloaded content. There may be more than one in a single Memory Pack.

xFB0-xFB1 = Licensee / Maker Code
xFB2-xFB5 = Program Type
xFB6-xFBF = Reserved
xFC0-xFCF = Title
xFD0-xFD3 = Block Allocation ...



BS-X uses a 32kb battery-backup SRAM. This is the BS-X SRAM Map. Everything is Little Endian, unless said otherwise. In the Memory Map, it's 10-17:5000-5FFF.

      Offset - Size (Bytes) - Description
  [Bank 0x10 - Dedicated to BS-X]
      $0000 - 0x02   - Always $4753 (String ...

Testing Code

[[!redirects Running your programming on Hardware]]

Once you've programmed a game or other bit of data for SNES, you'll probably want to try to, well, test it.


Although for most software these choices are, mostly, about preference. Most games which require [[Expansion Chips]] o ...

Nintendo Music Format (N-SPC)

N-SPC Player is a common SPC player included in many SNES games. The actual player N-SPC itself seems to vary slightly from game to game. Secret of Mana's internal music format can be thought of as a counterpart to N-SPC, as can [Seiken Densetsu 3]( ...