| When
it first shipped, the MWave Modem supported up to 14.4K data rates. A
free upgrade early in 1996 took it to 28.8K. Towards the end of 1996, a
33.6K update was released - publicly for certain Aptiva models and an
IBM internal beta for ThinkPads. The ThinkPad upgrade will be released
to customers soon, and all current MWave systems
will likely support some form of 56kbps modem late in 1997 once the
emerging PCM-based standard is ratified.
Note: Some 56K Modems will be available before then but they will probably be based on extensions to current V.34 technology rather than PCM. All this is possible because, uniquely in the Modem world, the MWave Modem is completely software-driven. Other implementations may be easier to configure initially, but hardwiring a Modem's logic or burning code in to EPROM makes speed-upgrading (and indeed bug fixing) difficult if not impossible. Hybrid implementations also exist in the marketplace (such as "WinModems"). These have some modem function - such as the critical Data Pump - hardwired in silicon, and use the main system processor to handle other functions such as compression and error-correction. Although this implementation is cost-effective and does permit upgrading/fixing the protocol functions, the maximum data rate is fixed and there can be considerable CPU performance degradation - 10% or more is likely. Not only that, one common implementation today (Compaq's Lucent Modem) does not offer native DOS, Windows NT or OS/2 support. In contact, MWave is supported on all popular operating systems. Finally, a note on modem peformance. Even though all modems may initially report a "connected at 33.6K" message, this is no guarantee of subsequent real data throughput. The recognised method of measuring actual throughput is the Network Model Coverage ("NMC") Score defined in ITU-T standard TSB37A. Here are some NMC scored for 33.6 modems:-
As many Bulletin Boards and Internet providers use US Robotics Courier modems, the following scores are also significant:-
These tests assume a "typical" national Ditigal telephone network, but another important performance factor is how well the modem handles Line Delay. This can be caused by intermediate analogue exchanges in a long-distance call, or satellite hops in an international call. One very popular chipset used in many modems today struggles when the line delay approaches 650ms - not uncommon. MWave readily handles worst-case 750ms line delays. |