programmable (Flash) type ROM memory (eg. USR Courier). In other designs   
       DSP code is stored in driver files on the user's system (eg. USR   
       WinModem, IBM MWave).   
      
          CAVEATS: In general, operational characteristics relative to basic   
          modulation functions are unalterable when "static" ROM is employed   
          (ie. bug fixes, changes in protocol implementation, or support for   
          new operational modes, cannot be accomplished without physically   
          changing the data pump).   
      
          The USR WinModem is a special case of the configuration where DSP   
          code is loaded in the form a a driver from the user's system in that   
          it is platform specific - it will only function under Windows   
          incarnations where virtual device drivers are supported (ie. Windows   
          3.X and Windows 95), IT CANNOT BE USED UNDER DOS, OS/2, WINDOWS NT,   
          OR ANY FLAVOR OF *NIX.   
      
       The controller section is typically composed of a general purpose CPU   
       and ROM where code governing the command interface, higher-level   
       protocols (eg. error correction and data compression), facsimile   
       functions, and ring pattern recognition, etc, are implemented. As is the   
       case with the DSP section, the type of ROM used varies. The typical   
       design employs fixed ROM, but many vendors have begun to use flash   
       memory in the high-end models. The controller section of the modem is   
       typically what is referred to when a particular model advertises that it   
       employs Flash ROM.   
      
   MNP - (M)icrocom (N)etworking (P)rotocol - a family of proprietary error   
   correction and data compression protocols developed by Microcom. MNP levels   
   1-4 are error correction protocols, and MNP level 5 is a complementary data   
   compression protocol which functions under MNP4 error control. NOTE: MNP   
   Levels 1-4 have been placed in the public domain by Microcom.   
      
      MNP1     Asynchronous, half duplex transfer.   
      MNP2     Error correction, asynchronous, full duplex.   
      MNP3     Error correction, synchronous.  Not a big win over MNP2 about   
               20%.   
      MNP4     Error correction, better throughput than MNP2-3. a modification   
               which rides on top of MNP2 or 3 to improve throughput.   
      MNP5     Simple data compression, about 2:1.   
      MNP6     Statistical duplexing and Universal Link Negotiation.   
               With V.29, modems can emulate full duplex operation.   
               Also supports fall-forward operation between two MNP modems.   
      MNP7     Data compression, about 3:1.   
      MNP8     MNP7 for pseudo-duplex modems.   
      MNP9     Data compression, about 3:1.  Includes V.32 technology. (?)   
      MNP10    Dynamic fall-back and fall-forward adjusts modulation speed   
               with link quality. Intended for use for cellular, but doesn't   
               work too well for cellular transmissions!   
      
   NYQUIST THEOREM - a fundamental dictum of data communications that governs   
   channel capacity. In simple terms it states that frequencies can only be   
   accurately reproduced at up to half the sampling rate. Stated differently,   
   the maximum theoretical signaling speed of a channel in baud is twice its   
   bandwidth.   
      
   Relative to the telephone system, it dictates that no frequency above 4kHz   
   can be transmitted over a typical phone line.   
      
   OCTET - An octet is a string of 8 bits, and not necessarily the same thing   
   as a byte. Communications switches transfer information by the octet. If you   
   are using a packet switch to transfer telex messages, then every 8   
   characters will occupy 5 octets. If you are transferring a binary file from   
   one PC to another, then every 8 characters will occupy 8 octets.   
      
   PCM - (P)ulse (C)oded (M)odulation, a method of encoding an audio signal   
   in digital format.   
      
   PEP - (P)acketized (E)nsemble (P)rotocol - a proprietary multi-carrier   
   high-speed modulation protocol developed by Telebit.   
      
   POP - (P)oint (O)f (P)rescence, a dial-in point for acessing an ISP.   
      
   POTS - (P)lain (O)ld (T)elephone (S)ervice - an ordinary voice quality   
   telephone line.   
      
   PROTOCOL - A protocol is a set of rules governing the communication and the   
   transfer of data between two or more devices.  The rules define the   
   handling of certain communication problems, such as framing, error control,   
   sequence control, transparency, line control, and start-up control.   
      
   The Technical Standardization Sector of the International   
   Telecommunications Union, (ITU-T) renders technical recommendations which   
   are typically adopted as standards by manufacturers of telecommunications   
   devices. The recommendations are referenced with an alphanumeric   
   designation of the form V.### which may also include a modifying suffix   
   such as "bis" or "ter" (meaning second and third respectively). The   
   suffixes signify a complementary modification or extension of an existing   
   like-numbered recommendation (eg. V.32 relates to modulation technology for   
   operation of modems on the GSTN at 9600 and 4800bps DCE rates, while   
   V.32bis modifies and extends the scope of V.32 to include rates of 4800,   
   7200, 9600, 12000, and 14400bps, plus add logic for enhanced retrain   
   turnaround). Similarly, but somewhat different, V.42 recommends   
   error-control methodology, and V.42bis defines data compression technology   
   which functions under V.42 error-control.   
      
   In addition to the standards established by ITU-T recommendations,   
   manufacturers offer products which feature proprietary modulation or error   
   control technology which may be technically and/or functionally superior to   
   the methods recommended by ITU-T.   
      
   RBOC - (R)egional (B)ell (O)perating (C)ompany, one of the "Baby Bell"   
   teleco operating companies created by the government mandated break-up   
      
   --- MPost/2 v2.0a   
    * Origin: Marsh BBS (c) Dawson Creek BC Canada (1:17/23)