
    The First Popular 14.4 Kbps Modem Gets Even Faster


      The Courier HST can transfer data at speeds up to 16,800 bps.  With
    V.42bis data compression, throughput can reach 57,600 bps.  On a typ-
    ical text file, it's about 52,000 bps; on compressed files speeds can
    achieve over 2000 CPS!.
      But what really makes the Courier HST the first choice of bulletin
    board services isn't speed. It's performance.
      The Courier HST uses powerful Intel 80188 microprocessors instead of
    the slower Z80s or 8031s.  It can easily handle all the computations
    involved in data compression and error control, even when it's going
    all out at 16,800 bps.
      And only a Courier gives you ASL - Adaptive Speed Leveling.  All
    modems have to slow down for phone line noise.  But two Courier
    modems can monitor the line and speed up again the moment conditions
    improve.
       With any other modem, you'd be stuck in low speed for the remainder
    of the transmission.  That can turn a $1 phone call into a $10 phone
    call.
       The Courier HST is designed to communicate asynchronously with all
    terminals, PC's, and mini computers on dial-up or two-wire leased
    lines. From 300 to 2400 bps, it's compatible with all popular CCITT and
    Bell standards. And it's compatible with the vast installed base of
    Courier HST modems at up to 16,800 bps.
        It uses a unique asymmetrical duplex operation, with a 16,800 bps
    data channel, and a 450 bps back channel.  It's not a "ping pong"
    scheme that operates at high speed in short bursts.  It sends and
    receives simultaneously, automatically assigning the high speed channel
    to the heavier data flow.  There are none of the delays typically
    associated with data acknowledgment processes.
       And because asymmetrical duplex uses less of the phone band than
    full duplex, the HST stands up to line noise better than any other high
    speed modem.
       A Courier HST makes the most of every second you spend on line!

       HIGH SPEED FEATURES AND BENEFITS


    High speeds: 16.8, 14.4, 12.0, 9.6, 7.2 and 4.8 Kbps in HST mode, with
    back channels at 450 and 300 bps.  There's nothing faster on dial-up
    lines.

    Maximum throughput: 57.6 Kbps. You can save up to 90% of the phone
    costs involved in file transfer.

    High speed compatibility: HST. You're compatible with the vast
    installed base of HST modems.

    Asynchconous transmission puts you in high speed communication with
    terminals, minis, and PC's.

    Demand-driven direction control automatically switches the high speed
    channel direction if data demand reverses.

    Asymmetrical duplex operation. The 16.8 Kbps data channel and 450 bps
    back channel are highly efficient for one-way file transfers, and
    still give excellent response when you're working interactively.


    STANDARD ON ALL COURIER HIGH SPEED MODEMS

    Features And Benefits

    COMPATIBILITY:

    CCITT V.22bis at 2400 bps.

    CCITT V.22 and Bell 212A at 1200 bps.

    CCITT V.23 at 600 and 1200 bps.

    CCITT V.21 and Bell 103 at 300 bps.

    You have on-line compatibility with all popular 300 - 2400 bps modems.

    ERROR CONTROL AND DATA COMPRESSION:

    CCITT V.42 error control.

    MNP Levels 2-4 error control.

    CCITT V.42bis data compression.

    MNP Level 5 data compression.

    You get 100% error-free data, and maximum throughput.

    Trellis-coded modulation is twice as effective as QAM in protecting
    your data against phone line noise.

    CONVENIENCE:

    Nonvolatile Random Access Memory. Easily programmable memory keeps
    user-defined configuration.

    Phone number storage gives you an auto-dial directory of four
    frequently used numbers.

    Auto Dial. Using the "AT" command set in asynchronous mode, you can
    dial or program from your keyboard.

    Auto Answer. You don't have to run for the phone or stand by a switch.

    Automatic Redialing will redial up to 10 times, automatically.  Useful
    if you know the modem you're calling is frequently busy.

    ASL (Adaptive Speed Leveling (tm)), up or down, gives you 100% error-
    free transmission at the highest possible speed under prevailing line
    conditions. Automatically selects the highest speed and error control
    protocol supported by the remote unit.  You get the maximum possible
    throughput, and you don't have to worry about compatibility.


    On screen help gives you instant answers to most questions without
    opening the manual.

    Externally accessible DIP switches. No disassembly required.

    RS232 pins 2 and 3 (Send and Receive) are switch-reversible.  Easy to
    use with terminal, computer or printer.  (Desktop models only.)

    Flow control allows fixed RS232-C rates up to 38.4 Kbps.  You're not
    confined by a slow port speed.

    12 LED front panel indicators. You can clearly see what your modem is
    doing. Diagnosing a problem is easy.  (None on internal models.)

    Built-in speaker with volume control. You can hear call progress.  (Not
    on rackmount models.)

    Bottom label help summary. Particularly helpful for setting dip
    switches. (Desktop models only.)

    Complete diagnostic capability. Local analog, digital loopback, and
    remote digital loopback self-testing make pinpointing a problem easy.

    U.S./CCITT answer sequences. You're compatible with the current
    standard.

    FOR YOUR INFORMATION

    Warranty: A full 2-year warranty on parts and labor, which you may
    extend indefinitely for a nominal fee.

    Package Contents: Modem, power adapter, RJ11C phone card, manual.

    IBM, IBM PC, IBM PC/XT, IBM PC/AT AND ISM Personal System/2 are
    trademarks of International Business Machines Corp. U.S.  Robotics and
    the USRobotics logo are registered trademarks, and Courier, Courier
    HST, Courier HST Dual Standard, Courier V.32bis, ASL, Total Control,
    and Rackmount 32 are trademarks of U.S.  Robotics, Inc. MNP is a
    registered trademark of Microcom, Inc.  Apple is a registered trademark
    of Apple Computer, Inc. UNIX is a trademark of AT&T Information
    Systems. Intel is a registered trade mark of Intel Corp.
    (c)1990, 1992, U.S. Robotics


