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 $7E9BEC)
[Everything is checked for the Checksum]
$00-$01 : "SF" (0x4653) string.
$02 : ???
$03 : ???
$04 : ???
$05 : ???
$06 : Number of Data Blocks (Goes to RAM $4B)
$07 : 8-bit Checksum.

Channel Map

(Data Block Header)
$00-$01 : 16-bit value, Software Channel ?.?.X.X
$02 : Number of Data Chunks in this block

(Data Chunk begins here)
$00 : Unknown
$01-$02 : Software Channel X.X.?.?
$03-$08 : Unknown
$09 : Data Settings
$0A-$0B : Hardware Channel
(From here, you can have another Data Chunk, or a Data Block header and repeats)

BS-X supported Software Channels

In Software Channel 1.1.?.? ($0101):
1.1.4.0 ($0400) = Message of the Day
1.1.7.0 ($0700) = Update Download
1.1.5.0 ($0500) = Main Download (Required)
1.1.6.0 ($0600) = Item/Schedule Download

Common Download Header

(Goes to $7E9A34)
$00 : AND #$F0 and goes to RAM $1414
$01 : Part Number (Goes to RAM $140E)
$02 : Goes to RAM $1411, must be #$00.
$03-$04 : Size of Data - 5. (Goes to RAM $140F)
$05 : Has to be #$01.
$06 : Number of Parts (Goes to RAM $1412)
$07-$09 : 24-bit Relative Address to Where the Data should be copied.
(Following Data goes to Hardcoded Address+$07)

Message of the Day

The Message of the Day, in Shift-JIS format, gets copied to RAM $7EA1B9

Update Download

Seems like it's used from updating BS-X BIOS functions on SRAM.

(Goes to RAM $7FC000)
$00 - Unknown.
(Main Copy Header starts here)
$01 - Check. Just don't put a negative value.
$02 - Unused.
$03-$04 : 16-bit Data Size. (Big Endian)
$05-$07 : 24-bit Address for Destination Copy. (Big Endian)
(From here, Main Data)
(Other Data to copy, 8 bytes after the last data, Main Copy Header again and repeats)

Main Download

ALWAYS DOWNLOADS THIS. It's used for the main part.

Following Data goes to $7EA31D, which then goes to $7EA21D (Check RAM Map)

Item/Schedule Download

(Goes to $7FC000, See Item/Schedule Format)

Program Download

Following Data is Game/Magazine Data.
Goes to $400000 or $C00000.