USRobotics x2/56K, 33600 user manual Reserved

		7	128	Reserved
Reg	Default	Function
S33	0	Bit mapped register setup for the 28.8 speed
		modems only. To set the register, see the
		instructions for S13.
		Bit	Value	Result
		0 (zero)1		Disable 2400 symbol rate.
		1	2	Disable 2743 symbol rate.
		2	4	Disable 2800 symbol rate.
		3	8	Disable 3000 symbol rate.
		4	16	Disable 3200 symbol rate.
		5	32	Disable 3429 symbol rate.
		6	64	Reserved.
		7	128	Disable shaping.
S34	0 (zero)	Bit mapped register setup. To set registers,
		see instructions for S13.
		Bit	Value	Result
		0 (zero)1		Disable 8S-2D trellis encoding
		1	2	Disable 16S-4D trellis encoding
		2	4	Disable 32S-2D trellis encoding.
		3	8	Disable 64S-4D trellis encoding.
		4	16	Disable non-linear coding.
		5	32	Disable TX level deviation.
		6	64	Disable Pre-emphasis.
		7	128	Disable Pre-coding.
S35-
S37	Reserved.
S38	0	Sets an optional delay, in seconds, before a
		forced hang-up and clearing of the Transmit
		buffer when DTR drops during an ARQ call.

This allows time for a remote modem to acknowledge receipt of all transmitted data before it is disconnected.

Default 0: the modem immediately hangs up when DTR drops.

54 Sportster Winmodem 33600 & x2/56K - User's manual