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[aprssig] APRSDOS and Soundcards

Stephen H. Smith wa8lmf2 at aol.com
Tue Jan 16 02:26:25 UTC 2007


bruninga at usna.edu wrote:
> Sorrry, APRSdos does not have hooks to a sound card.  Simplest
> thing I can think of is to use a D7 HT with it's internal TNC.
> SO as, you say, all you have to buy is a "radio"...  But it has
> to have the TNC built in.
>
> Bob
> WB4APR
>
>
>   

No APRS or packet application has "hooks to a sound card".   They only 
need KISS or TCP/IP support.  The soundcard softmodems appear to other 
programs either as a KISS TNC device on a virtual serial port (MixW or 
AGW Packet Engine), or as a TCP/IP network device (AGW Packet Engine).


The fundamental problems with using soundcard softmodems in DOS is:


1)  RAM Cram.     DOS basically can only use the first MB of RAM no 
matter how many GBs of ram are in the machine.  It's simply not enough 
memory for the main application plus the soundcard hardware drivers plus 
the soundcard modem application.  [The driver alone for the typical 
sound card today would more than fill the ENTIRE DOS memory space!]


2)  DOS is not multitasking.  Normally only one program at a time can 
run in DOS, aside from some minor background pop-up RAM-resident 
utilties. One would have to rewrite an application like AGW or MixW to 
be a monster device driver, rather than a stand-alone program running 
alongside DOSaprs.    Recall the old DOS games. Each one had it's own 
internal sound and video drivers. If your particular sound and video 
hardware wasn't supported by a particular game, it would never work with 
it.




--

Stephen H. Smith    wa8lmf (at) aol.com
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