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Chapter 3 - Basic Modem Operation
3-8
AT Command Description
E1 Echoes command characters
&C1 Carrier detect follows remote carrier
&D2 Modem disconnects on DTR on-to-off transition
&K4 Use both V.42 and MNP 4 error correction, and use
both V.42bis and MNP 5 data compression
&N0 Modem negotiates highest possible connection speed
ZyXEL Serial/Parallel I/O Card
For high-speed PC to modem communication, ZyXEL produces the special I/O
adapter card. This card includes a serial port and a parallel port, each with
special features, particularly when working with a ZyXEL modem, for example:
The serial port is 16550-compatible for most comm software's usage. It has a
speed of up to 460.8Kbps and data loss errors will not occur when working with
a ZyXEL modem's serial port. This solves high-speed communication problems in
Windows and other multi-tasking systems. The serial port has a 32-byte
transmission and a 32-byte receival FIFO to increase any comm program's
efficiency.
Helpful Hints for Mac Computers
Special AT Command Settings for Mac
For operation with Mac computers, you may use the factory default settings with
one exception. You must set the modem to ignore the DTR signal as follows.
Type:
AT&D0<enter> (set modem to ignore DTR)
AT&WZ<enter> (saves the settings to power-up profile)
Mac Serial Port
When you connect your Omni 288S modem to a Macintosh computer, make sure
the cable is a hardware handshaking cable. These cables are readily available.
The models Lisa, Macintosh 128 and Macintosh 512 don't have hardware
handshaking. The serial port on these (very outdated) models is provided as a 9-
pin connector similar to that of a PC. The serial port on all other Macintosh
models is a Mini-8.
Mac Software Tips
All terminal programs which make use of the hardware handshaking feature can
be used on the Apple Macintosh. Such programs are readily available as PD,
shareware or commercial software. One of the most powerful shareware
programs available is ZTerm.