AT&Vn

Views the settings in profile (n-1); n=0 to 5; n=0 views

 

current settings.

AT&Wn

Stores the current settings in user profile ‘n’; n=0 to 3.

ATZn

Resets the current settings with the settings in profile ‘n’,

 

n=0 to 4.

Profiles 0 to 3: User profiles.

Profile 4: Factory default profile.

Helpful Hints for PC Computers

Most PCs are equipped with more than one serial port. Standard cables are readily available from many suppliers. Usually, serial ports are manufactured in two forms, either with a 25-pin male jack or a 9- pin male jack. For high speed serial connections at 230.4Kbps or 460.8Kbps, use a low-capacitance cable. Also, keep the cable as short as possible.

The serial port is driven by interrupts. Every interrupt needs a certain amount of overhead processing time. Too many interrupts reduce the computer's efficiency. The UART 16450 is very commonly used in serial port devices. For every character (byte) received, it generates an interrupt. If your hardware allows it and if your software supports it, replace the 16450 UART with a 16550 model. This newer chip has an internal buffer and generates an interrupt for up to every 16 characters (several trigger levels are available). With this UART installed, you may drive your serial port at 57600 bps and above.

While data is written from the transfer-buffer to your hard-disk, characters may be lost at the serial port. This is due to the fact that disk-access interrupts have a higher priority than serial port interrupts. If you are running at a high serial speed, e.g. 230.4Kbps or 460.8Kbps,

22 Basic Modem Operation

Page 35 Page 37
Page 36
Image 36
ZyXEL Communications U-336SA user manual Helpful Hints for PC Computers
Page 35 Page 37

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.
Top Page Image Contents