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Outside of hardware failure, many connection problems associated with a modem are not problems with the modem, per se, but problems 1) of compatibility between the modem and the cpu, 2) of the configuration of the modem, or 3) of the software used to control the modem. A list describing the set of connections problems related to these three would include:

• Modem does not initialize or is unresponsive
• Modem handshake, the squawking noises made when two modems first connect, does not complete
• Connection does not come up after the handshake has completed
• Connection drops frequently
• Speed of connection is not as high as it should be

The symptoms above do not always indicate a compatibility, configuration or software problem, but in many cases they do. When other avenues have been exhausted, a good step to take when troubleshooting is to find out, yourself, through a friend or with the help of Green Apple, what information is available for your modem online.

This document, The Modem Resource Database, is meant as a resource for helping in the process. It is designed to provide a basic understanding of modem types, their operation, and what you need to know for upgrading and where to find upgrading information.

As 56K-type modems are the most common modems seen in the marketplace, the modems in widest use, and the modems about which we see the most problems, the focus of the document is on them. However, much of what is found here is applicable to other (33.6Kbps and earlier) modem types. Similarly, the document is written from the perspective of Win95/98 operating system, but is applicable in large part to modems used in other operating systems.

Design Of A Modem

The design of a modem can be broken into six functional components:

1. Line Codec: Analog to digital coder/decoder. Transforms the analog signal, an oscillating electrical wave varying continuously in frequency, phase and amplitude, into a digital signal, a discrete set of 0's and 1's. And vice versa.
2. Digital Signal Processing (DSP) Data Pump: Responsible for the processing of the digitized waveform. The Data Pump performs error checking and correction, and flow control, and carries out the modem protocol (e.g. V.90, X2, K56Flex).
3. Controller: Responsible for managing the sync to async communications between the data pump (sync) and the COM port (async).
4. Bus Interface: The electrical throughway for the digital signal to travel from the modem to the rest of the computer. With external modems, the bus interface will follow RS-232 (DB-9/DB-25) specs; with internal modems, the bus interface will follow ISA or PCI specs.
5. Modem Driver: The software interface between the modem and the modem handling features of the operating system, features which applications invoke when they want to use the modem.
6. Firmware: The computer code used by the data pump which has the rules implementing the modem protocol in use (e.g. the V.90, X2, K56Flex rules). Firmware is used only in modems having a data pump. It is stored on a permanent or semi-permanent basis on a ROM or EPROM chip in the modem itself.

Characterizing A Modem

Modems can be characterized in a number of ways. Some useful ways of doing so are by Location, Speed, Bus Interface, Data Pump, Controller, EPROM, and Modem Protocol.

Location - Where's the modem?
Internal or External. An internal modem is a card which sits in an ISA or PCI slot on the motherboard inside the computer. Internal modems will be cycled on and off with the cycling of power to the machine. An external modem sits outside the computer. External modems generally have their own power supply and on/off button. An external modem connects to the computer via a serial cable from it to an external COM port on the computer.

Speed - What is the maximum speed of the modem?
14.4Kbps, 28.8Kbps, 33.6Kbps, or 56Kbps. Kbps=Kilo-bits per second. Each number represents the maximum transmission rate of a modem under optimal conditions (the 56Kbps figure is inaccurate: the maximum rate of a 56K modem is actually about 53Kbps).

Bus Interface - How does modem communicate with the computer?
RS-232 or ISA/PCI. RS-232 (DB-9/DB-25) is used by external modems which connect to the computer via a serial port and cable. ISA/PCI is used by internal modems which plug directly into an ISA or PCI slot on the computer's motherboard.

Data Pump - Does the modem have a data pump?
A modem having a data pump will have a chip on it which handles the digital signal processing. A modem without a data pump on it has the signal processing performed via a virtual device driver (.vxd) running on the cpu. Every external modem has a data pump; only internal modems may not have a data pump. Modems without a data pump will also not have a controller. Such modems are called 'Host Signal Processing (HSP)' modems or 'Software' modems. HSP modems need the Intel MMX chipset to perform the digital signal processing. All HSP modems are implemented on PCI cards. As HSP modems are relatively new, it is likely that they will implement some 56K protocol (usu. V.90): 33.6 HSP modems are very rare. PCTel, Cirrus, Aztec and Rockwell/Conextant (SoftK56) all manufacture HSP modems or chipsets.

Controller - Does the modem have a controller?
A modem having a controller will have a chip on it which handles the sync to async communication between the data pump (sync) and the COM port (async). With an external modem, the COM port is on the outside of the computer and connects to the modem using a serial cable. With an internal modem, the COM port is located on the modem card itself. Controllerless modems do not have such a controller chip; instead, control functions are implemented through a virtual device driver (.vxd) running on the cpu. As well as handling sync to async communications, the driver emulates a COM port, as both the operating system and application software are written to communicate with a modem through a COM port. All external modems have a controller; only internal modems may be controllerless. Controllerless modems are commonly known as 'Winmodems'. 3Com/U.S. Robotics Winmodem, Lucent Winmodem, and Rockwell/Conexant HCF modems are all examples of controllerless modems.

**Note: Modems having both a data pump and a controller are called 'Hardware' modems. Accordingly, all external modems are Hardware modems. Most non-56K ISA modems are Hardware modems (with the exception of the 33.6 USR Winmodem); ISA 56K modems are split evenly between Hardware modems and Winmodems. Most PCI modems are either Winmodems or HSP modems (at present only a couple PCI Hardware modems are manufactured).

EPROM - Is the modem software upgradeable?
The data pump of modems having a data pump actually runs a small piece of computer code. This code is the modem's firmware. Firmware is kept on the modem on a Read Only Memory, ROM, chip or an Erasable/Programmable Read Only Memory, EPROM, chip. A modem having its firmware kept on a ROM chip is not software upgradeable; that is, you cannot run a program to upgrade the modem firmware. A modem having its firmware kept on an EPROM chip is upgradeable. The process of upgrading a modem's firmware is called 'flashing'. Old modems were not generally equipped with EPROMs and cannot be flashed; almost all recent 56K Hardware and Winmodem modems use EPROM for storing firmware and can be flashed. HSP modems do not have data pumps; thus, they do not have EPROMs and are not flashable.

Modem Protocol - What protocols does the modem support?
V.90, X2, K56Flex, V.34, or V.42. Modem protocols are the rule sets which govern a communication session between two modems. Both modems must support a given protocol if they intend to use that protocol when speaking with one another. V.90 is the standard 56K protocol.

Schematics Of Hardware Modem, Winmodem And HSP Modem

Hardware modem (external):
codec <> data pump <> (sync) controller (async) <> RS-232 (DB-9/DB-25) bus interface <> COM port <> driver

Hardware modem (internal):
codec <> data pump <> (sync) controller (async) <> ISA bus interface (PCI very infrequent) <> modem COM port <> driver

Winmodem (always internal):
codec <> data pump <> ISA or PCI bus interface <> virtual controller/COM port (.vxd) <> driver

HSP modem (always internal):
codec <> PCI bus interface <> virtual data pump (.vxd) <> virtual controller/COM port (.vxd) <> driver

Software Needed By Modem Type

Modems need some combination of modem driver, firmware and/or virtual device driver (or drivers). Most websites which have modem software available for download will separate the firmware from the drivers. Firmware is delivered in the form of a loader which is ran once, and only once, to install the firmware code into your modem's EPROM. Before flashing your modem, be absolutely sure you have the correct firmware, and, once the flash process has begun, do not interrupt it: loading bad firmware or interrupting a firmware load will ruin the modem. The modem driver and any virtual device (.vxd) drivers used by the modem are often bundled together in one self-extracting archive. Below is the kinds of software you should look for given a particular modem type:

Hardware modems (external and internal):
   14.4K: Will not need any software
   28.8K/33.6K: Possibly V.34 firmware and driver upgrade
   56K: V.90 firmware. V.90 Modem driver

Winmodem:
   33.6K: V.34 firmware. V.34 virtual controller and modem driver
   56K: V.90 firmware. V.90 virtual controller and modem driver.

HSP (Software) Modems:
   56K: V.90 firmware. V.90 virtual controller, virtual data pump and modem driver

When To Consider Upgrading Modem Software

If you notice your Internet connection suffers from any of the problems listed at the beginning of this document, and you cannot determine any other source for the problem, checking to see if the modem has a new firmware or driver available is a good idea.

This is particularly true for 56K modems. Firmware and drivers for this class of modem are continually being upgraded as manufacturers make improvements to their implementation of the V.90 standard. In addition, even if your 56K modem connects okay, it is good to check for new software every couple of months.

With older modems (33.6Kbps and earlier) the case is somewhat different. Many were not built with upgradeable EPROMs. Further, most manufacturers long ago stopped making changes to the software as it had reached a high level of maturity. For the most part, the modem firmware will be suitable, unless you purchased an early release of either a 28.8 or 33.6 modem, in which case, checking for available firmware upgrade is a good idea. Regarding the driver for older modems, generally a driver from the driver set included with Win95/Win98 is the one to use. The exception to this are 33.6 Winmodem and 33.6 HSP modems.

Where To Find Modem Information And Upgrades

Finding information or software upgrades for a modem is not always a straight-forward process. Green Apple recommends the following recipe for searching the web:

1. If the machine is from a major PC manufacturer and the modem came installed, check the PC manufacturer
2. Check the modem manufacturer (a note on finding the modem manufacturer is included towards the end of this document)
3. Check a generic driver distribution site
4. If using a V.90 modem, check a V.90 resource site
5. Check modem chip manufacturer

Finding A Modem Manufacturer

All recently-made modems are required by the FCC to have affixed to them an FCC ID. In order to search for information or software on a modem you will almost always need to know the modem manufacturer. When it is not clear who the manufacturer is, the ID can be used to search the FCC database to find out.

The FCC ID search page is at: www.fcc.gov/oet/fccid

Help on using the FCC ID search page is at: www.fcc.gov/oet/fccid/help.html

If the modem has an FCC ID, it will be on a sticker on the modem itself. To find the ID for external modems, just check the modem case. For internal modems, the computer case must be opened and the card examined.

Related Green Apple Resources

For information on troubleshooting a connection problem, please see:
    www.greenapple.com/support/library/ConnectivityDiag.htm

For information on V.90, please see
    www.greenapple.com/support/library/V90.htm

For information on configuring an Internet connection for your operating system, please see
    www.greenapple.com/support/library

 
This document is copyright Green Apple, Inc, 1995-2007.  Permission is granted for the free distribution of it provided that its contents, including this notice, are not in any way altered. Green Apple disclaims all responsibility of fitness and suitability of this document. User is responsible for any software they download or install. It is incumbent upon User to read and obey copyright and licensing notices of all the software they use.
 

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