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Thu, February 12 2004 11:44 PM

Last modified:
Sat, April 23 2005 3:10 PM

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Suggested Modems for use with Texas Communications

If you have any questions or problems or need assistance, you may contact our technical support staff at the numbers listed on your Startup Kit or on our contact page. We highly recommend hardware modems for use with our system. A Lucent or Agere software modem is good as long as your computer is fast enough. Most software or "winmodems" will work but the vast majority will not perform nearly as well as the hardware variety. The following modems have been tested personally by us.

Modem Suggestions

These are in the order of what we found to be the best price/performance for internet connectivity. If you want other functions such as voice or speakerphone capabilities look closely to make sure the modem you choose has those functions. We suggest buying them from a local computer shop. If they are not abvailable there, you might try an online resource like Pricewatch.

Modem Suggestions - best performance for the dollar first
Name and ModelPrice
Lucent/Agere 56K v.92 PCI internal software modem*About $16
3Com USR 2977 56K v.90 PCI internalAbout $42
3Com USR 2976 56K v.90 PCI Data/Fax/Voice internalAbout $55
* Requires a 266 MHz computer

Differences in types of modems

There are many differences between the different types and brands of modems in relation to cost, performance, and reliability. These differences can be summerized as follows:

  1. Hardware
    Hardware modems perform well on any type of computer. They require no CPU (processor) cycles or power to perform the task of modem communications. They will almost always work more reliably, faster, and have fewer connection problems than other modems.
    • Are often called "real","hardware", or "controller" modems
    • Use real integrated circuits on which the modem's functions resides
    • Handle all error correction and compression on board without CPU help
    • Have Digital Signal Processor (DSP) chips on board
    • Usually have "flash" memory on board to store important instruction sets
    • Have an on board controller
  2. Software
    Software modems need quite a lot of CPU speed to work well. It is typical for these modems to use 50% or more of a processors cycles to perform its task. These type of modems work well only on fast computers with a lot of extra spped which is not being utilized. Even if the speed is available they still have many issues with poorly written drivers and modem software. The issues mentioned cause them to connect with some ISP's and possibly not at all with others.
    • Are normally referred to as "winmodems", "software", or "host-based"
    • Provide an interface to the phone line on board and little else
    • Often have hardware compatability issues which affect use or performance
    • All errror correction and compression is handled by the CPU and software
    • Some have on board DSP's but very few
    • Most have no flash memory, all instructions are in the software
    • Have no on board controller's
    • Vary widely in the quality of the connections they produce by:
      • CPU speed - minimum of 300MHz is an absolute must.
      • How well the software is written
      • Other hardware on the system and their settings
      • Other applications being run on the system
    • Sometimes identified as "HCF", "HSF", "HSP", or "winmodem"

Ideal expectations for winmodems

Microsoft has a page dedicated to what software modem and pc makers should ideally shoot for in the design of these devices. Most don't meet these. It should serve as a pretty good wake up call for those wanting one. Some excerpts are below. Find the full text version here. The jist of the whole document is that the only redeeming value of software modems is cost, and even that in many cases isn't realized when considering the additional CPU power that must be available for these modems to work.

"First, the early implementations have been fragile: connections not being made, connections being dropped, and memory leaks were all common problems. The newest CPUs have enough surplus CPU bandwidth; but legacy PC designs do not and are therefore slower. PCI 2.2 is not widely implemented yet, so hungry graphics card drivers can use up bus bandwidth and hold off modem drivers long enough to lose data. Some soft modem implementations hold off other drivers too long from interrupts or from thread execution; many of these soft modems are also vulnerable to similar behavior by other drivers such as soft DVD and soft audio drivers."

"Peak CPU usage should not exceed 50 percent in data transmission nor 75 percent in (re)training."

"These numbers apply to the minimum CPU specified in PC 99, which is a 300 MHz processor. If a driver that meets these guidelines is run on a slower processor, the driver performance could be so bad that the rest of the system might not run at all. Also, a CPU that has aggressive power management or thermal management might run slower. In such a system, the same performance problems would be compounded. A good rule of thumb would be to use these design guidelines for any slower processor."

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