[aprssig] What is "TNC Channel Switching"?

[Stephen H. Smith]

On 4/11/2014 10:54 AM, Andrew Pavlin wrote:
> Actually, there would be a reason to prohibit if the Kamtronics units couldn't handle it; they couldn't_transmit_  such packets to RF.
>
> But what software could attempt to send such packets in Command or Converse mode on a KPC? Nothing modern.

Decades old programs still in use such as APRSplus, WinAPRS, UIview, and more 
recent ones that don't support KISS such as APRSpoint.


  KISS mode wouldn't have a problem.
>
> Andrew, KA2DDO
> Sent from my Verizon Wireless BlackBerry

By no means does everyone on APRS use KISS mode interfaces.  For example, most 
of the numerous generations of firmware for the MFJ 127x family of TNCs and 
most generations of the "official" TAPR TNC2 firmware DON'T support KISS mode 
at all.  Many of these TNCs are still in use.    Not to mention the Kenwood 
D700 and TH-D7, who's KISS mode was basically unusable.   When any of these 
devices are used on APRS with external software, it will be in the classic 
command-line mode.

Any APRS software fielded today STILL has to assume a significant number of 
users will running in the terminal-like command-line mode instead of KISS.

[Remember that APRS is basically a kludge layered on top of a kludge to allow 
machine-to-machine communications over a protocol originally designed for 
human-typed keyboard-to-keyboard communications invented 35 years ago.   All 
being run on a lot of legacy hardware with unchangeable firmware that isn't 
going away anytime soon!]

It's what IBM once called   "the tyranny of the installed base"   when the 
radioal (for the time)and arguably significantly-improved hardware changes of 
the PS/2 family PCs in the mid-to-late 1980's flopped massively. (ISA and PCI 
cards wouln't fit into the "microchannel" slots of these machines.)