DCC by the Numbers

Address range		Additional byte	Purpose
From	To	Additional byte	Purpose
0 0 0 0 0 0 0 0 (0x00)	0 0 0 0 0 0 0 0 (0x00)		Broadcast
0 0 0 0 0 0 0 1 (0x01)	0 1 1 1 1 1 1 1 (0x7F)		7-bit (2 digit) multi-function decoders
1 0 0 0 0 0 0 0 (0x80)	1 0 1 1 1 1 1 0 (0xBE)	adx/function	9-bit Basic accessory decoders / 11-bit Extended accessory decoders
1 0 1 1 1 1 1 1 (0xBF)	1 0 1 1 1 1 1 1 (0xBF)	adx/function	Broadcast to accessory decoders
1 1 0 0 0 0 0 0 (0xC0)	1 1 1 0 0 1 1 1 (0xE7)	8-bit lsb	14-bit (4 digit) multi-function decoders
1 1 1 0 1 0 0 0 (0xE8)	1 1 1 1 1 1 0 0 (0xFC)		reserved for future use
1 1 1 1 1 1 0 1 (0xFD)	1 1 1 1 1 1 1 0 (0xFE)		see S-9.2.1.1 Advanced Extended Packet Formats
1 1 1 1 1 1 1 1 (0xFF)	1 1 1 1 1 1 1 1 (0xFF)		idle packet

Command byte								Description	Number of data bytes
7	6	5	4	3	2	1	0	Description	Number of data bytes
0	0	0	0	C	C	C	D	Decoder Control	1
0	0	0	1	C	C	C	C	Consist Control	1

0	0	1	0	X	X	X	X	16 reserved	0
0	0	1	1	0	X	X	X	8 reserved	0
0	0	1	1	1	0	X	X	4 reserved	0
0	0	1	1	1	1	0	0	1 reserved	0
0	0	1	1	1	1	0	1	Analog functions	2 : CH val
0	0	1	1	1	1	1	0	Restricted speed	1 : EN 28spd
0	0	1	1	1	1	1	1	128 step speed and direction	1 : dir & spd

0	1	0	X	X	X	X	X	Reverse 28 step speed	0
0	1	1	X	X	X	X	X	Forward 28 step speed	0
1	0	0	X	X	X	X	X	Functions F1-F4	0
1	0	1	X	X	X	X	X	Functions F5-F12	0

1	1	0	0	0	0	0	0	Binary States long form	2
1	1	0	1	1	1	0	1	Binary States short form	1
1	1	0	1	1	1	1	0	Function F13-F20	1
1	1	0	1	1	1	1	1	Function F21-F28	1

1	1	1	0	0	0	X	X	CV access, long form, reserved function	2
1	1	1	0	0	1	X	X	CV access, long form, verify byte	2
1	1	1	0	1	0	X	X	CV access, long form, write byte	2
1	1	1	0	1	1	X	X	CV access, long form, bit functions	2
1	1	1	1	X	X	X	X	CV access, short form	1

Second data byte								Description
7	6	5	4	3	2	1	0	Description
0	A10	A9	A8	0	A7	A6	0	Extended decoder. Address bits A5-A0 are in the address byte
1	A8	A7	A6	C	D	D	D	Basic decoder. Address bits A5-A0 are in the address byte