Power switch, turns the modem ON or OFF.

POWER JACK

Input terminal for power. Use the supplied AC adapter for U-336S model. For U-336SA model you can use your power cord to directly connect to the AC power outlet.

LINE

Dial-up line RJ-11 terminal jack, for connection to a 2-wire dial-up or 2-wire leased line.

PHONE

RJ-11 terminal jack, for connection to a telephone set.

EIA-232D

Serial port DB25S connector, for connection to the serial port of a DTE (computer/terminal). Pin assignments are listed in Chapter 12 Connector Pinouts for your reference. The signal-pin assignments for RJ-11 phone jacks are also listed in Chapter 12 Connector Pinouts.

Modem Connection

When you connect your U-336S modem to the power line, make sure you only use the power adapter that is supplied with this unit. Use of another adapter may not allow your modem to operate and could result in serious damage to the unit.

This adapter is rated for direct connection to an AC power outlet. Connect your modem as shown in Figure 2-5 U-336S Modem Connections.

10 Installation

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ZyXEL Communications U-336SA user manual Modem Connection, ∙ EIA-232D

U-336S, U-336SA specifications

ZyXEL Communications, a leading global provider of networking and cybersecurity solutions, has offered a range of products designed to cater to various connectivity needs. Among these, the U-336SA and U-336S modems stand out for their reliability and performance, particularly in the dial-up category during the heyday of internet access.

The U-336SA and U-336S modems are external devices that revolutionized the way users connected to the internet in the late 1990s and early 2000s. Designed for both home users and small businesses, these modems supported 33.6 Kbps data transfer rates, which, at the time, were considered cutting-edge. This capability allowed for reasonably swift internet browsing, email communication, and file downloads compared to earlier modems.

One notable feature of both the U-336SA and U-336S models is their plug-and-play functionality. This ease of use made them accessible to even the less tech-savvy users, allowing quick and straightforward installation. Users could connect the modems to their PCs or laptops via a standard serial interface, minimizing setup time and complexity.

Additionally, both modems were equipped with error correction and data compression technologies. The V.42 and V.42bis protocols enhanced data integrity during transmission, ensuring that users experienced fewer disruptions and greater reliability in their connecting experience. This was particularly vital for tasks like file transfers and large downloads, where data integrity was paramount.

The modems also featured compatibility with various operating systems, including early versions of Windows, which expanded their appeal to a broader audience. The U-336SA was specifically engineered as a standalone device, while the U-336S could often be used with existing computer systems, showcasing versatility in various deployment scenarios.

In terms of design, both modems were compact and lightweight, allowing for easy portability. This made them suitable for users who required connectivity on the go or in different locations.

Ultimately, the ZyXEL U-336SA and U-336S modems represent a significant technological achievement in the history of internet connectivity. Their introduction set the stage for subsequent advancements in modem technology and played a crucial role in the evolution towards broadband and high-speed internet access that we enjoy today. Their legacy endures in the foundational technologies and protocols that continue to drive modern telecommunications.