MODEMS AND THE 95LX: THREE COMMON PROBLEMS

There are three problems with using modems with the 95LX. First, battery powered modems look for the computer to assert the DTR line. The modem uses that as an "ON" switch. Since the 95LX doesn't have a DTR line, most battery powered modems will never turn on.

The WorldPort works because it can look at the TXD pin instead of DTR. (Other modems can be made to work by running a line from the modem's battery to the DTR pin, thus fooling the modem.)

Second, line powered modems (the kind with no battery and no AC power) expect to get their power from the RS-232 interface. The 95LX doesn't have enough power to share.

Third, many modems expect hardware handshaking (via RTS/CTS). The 95LX doesn't support this handshaking protocol. Most modems allow the user to disable the RTS/CTS handshaking, but many of them only let you disable it from a system that supports RTS/CTS. (You could wind up having to do the initial configuration using a PC to drive the modem.)

Ted Dickens (HP Forum Sysop)

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