3Com 56K manual Disable preemphasis, Enable ring type a, Enable ring type B, Enable ring type C

I-8APPENDIX I: S-REGISTERS

Register	Default	Function
S56	0	Bit-mapped register primarily used by 3Com Technical
		Support for debugging purposes.
		Bit	Value	Result
		0	1	Disable non-linear coding.
		1	2	Disable TX level deviation.
		2	4	Disable preemphasis.
		3	8	Disable precoding.
		4	16	Disable shaping.
		5	32	Disable V.34+.
		6	64	Disable V.34.
		7	128	Disable V.FC.
S58	0	Bit-mapped register primarily used by 3Com Technical
		Support for debugging purposes.
		Bit	Value	Result
		0	1	Disable x2.
		1	2	Reserved.
		2	4	Reserved.
		3	8	Reserved.
		4	16	Reserved.
		5	32	Disable V.90.
		6	64	Reserved.
		7	128	Reserved.
S70	0	Bit-mapped register primarily used by 3Com Technical
		Support for debugging purposes.
		Bit	Value	Result
		0	1	Enable ring type A.
		1	2	Enable ring type B.
		2	4	Enable ring type C.
		3	8	Enable ring type D.
		4	16	Reserved.
		5	32	Reserved.
		6	64	Reserved.
		7	128	Reserved.