-=> Quoting John Clarke to Russell Brooks <=-

 JC> On Nov 24, 1996 at 08:23 hrs, Russell Brooks of 
 JC> 3:640/305.55 wrote to John Piper:

 JC> Hello Russell,
 
 BG>>> Not specifically, but they do appear to be pretty heavily into some
 BG>>> less than salubrious business practices of late, as shown by their
 BG>>> complete lack of action re their seemingly never-ending succession 
 BG>>> of buggy Sportsters, as well as their outrageous pricing on Couriers,
 BG>>> not to mention their decision to charge Courier owners for the x2 
 BG>>> upgrade when previous SDLs have been free.
 
 JP>> This is completely new to me. I didn't know there would be a charge to 
 JP>> obtain the SDL containing the x2 code. I hope this doesn't become a 
 JP>> trend.
 
 RB> I have been informed that I will be getting mine upgraded FREE.
 RB> Although many will have to pay up.

 JC> A note of caution before you race off and have your modems converted.

 JC> In Oz we use the European standard 64Kb/s digital links while USA uses
 JC> US  standard 56Kb/s digital links.  Both standards are ratified 
 JC> by the ITU-T BUT the two are NOT compatible.  Any modem 
 JC> converted to the USR 56KB/s standard would ONLY be usable 
 JC> in the USA.

 JC> Unless you want to sell the modem to someone in the USA 
 JC> when you have finished with it, having the conversion done 
 JC> would be a waste of time and money (freight costs) IMHO.

Its only going to be an SDL upgrade and it is no more likely to make the
modem unusable as the fact that it has HST...

Also, the USA DOES have 64kbit ISDN - the Courier I-Modem for example which
is only available in the US is capable of operating at 64k as well as 56k
and a number of other slower speeds.  The reason why there is a 56k limit on
this technology is not because of 56k digital links, but is actually because
of the u-law encoding that is used.  u-law and a-law encoding put more 
quantization levels near 0 volts which are harder to distinguish than
those quantization levels away from 0 volts, so instead of getting 256
levels per sample you will get far less with a net reduction in transfer 
speed.  The Rockwell white paper probably explains this better than I have.

If this technology were running over a 56k digital link you would probably
be limited to a speed of 48k.  You only get 56k digital links when "bit
stealing" occurs.

The main difference between the US and here is the fact that they use 
u-law encoding while the rest of the world uses a-law.  A-law is only 
different in the spread of quantization levels and should not require much
modification of the technology to work over here.  In fact, USR announced
support for a number of countries including Australia although it remains
to be seen how soon this occurs...

As far as the issue of whether the modems will still be "modems", I think
that they still will be a lot closer to normal modems than terminal adaptors
since the modem will still be using normal analogue modem technology for the
back channel and most of the normal analogue functions in the 
"demodulation" stage.

Regards,
Mark Griffiths.

... Not tonight, dear.  I have a modem.
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