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Re: MSDOS 3.2 COM ports

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On Saturday, April 24, 2021 at 12:08:50 PM UTC+10, Grant Taylor wrote:

> > Could you please explain what this means? A program wishing to open 
> > a COM port is meant to do a special "device open" or something?

> Well, NUL, CON, COM1, COM2, COM3, COM4, LPT1, LPT2, and LPT3 are special 
> reserved device names in DOS. (I think COM goes up to 4.) 
> 
> You could do something crude like "COPY CON MYFILE.TXT" start typing, 
> and copy would copy from the CONsole into MYFILE.TXT. I think you use 
> Control-D to indicate end of file. 
> 
> Similarly, you can use "COPY MYFILE.TXT CON" as an alternative to TYPE. 
> DOS dutifully copies MYFILE.TXT to the CONsole. 

Ok, which means a normal call to fopen() thus open()
would accept that name.

> > So is there a DOS interrupt to do the equivalent of the mode command?

> I have no idea.

I think there would have to be, as I assume "mode" is a
separate executable meaning it has to do an interrupt
to do its work.

> > I can remember when I wrote a comms program for MSDOS, I bought 
> > a comms package, can't remember the name, from the guy who created 
> > "Texas Zmodem", and he mentioned to me that there shouldn't be a need 
> > for a comms package like his, it should be built into MSDOS. And I'd 
> > like to understand what the issue was.

> I wonder if he was implying that the MS-DOS was missing some 
> functionality or what. 

Sorry, maybe I should have said "comms library". It was an
API to interact with the serial port, because MSDOS
supposedly didn't have that ability.

Maybe it was just interrupt-driven capability that was missing.

> Technically speaking, I suspect that you /can/ interact with a modem, a 
> la. a serial device, via the COM# port. But copy, as outlined above is 
> inherently uni-directional. 

I wonder if that was the limitation, and all that is required
is to extend MSDOS (via PDOS/86 or whatever) to allow
a COM port to be opened read/write, and you just need
to do a rewind() when switching between the two modes.

I think I can devise a strategy based on that.

With the assumption that the remote is more sophisticated
than PDOS/86 and will coddle PDOS/86 communication.

My plan is to basically run a "BBS" on my Windows box
for PDOS/86 to communicate with via the serial port.

BFN. Paul.

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Thread

MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-23 16:19 -0700
  Re: MSDOS 3.2 COM ports Grant Taylor <gtaylor@tnetconsulting.net> - 2021-04-23 18:26 -0600
    Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-23 18:47 -0700
      Re: MSDOS 3.2 COM ports Grant Taylor <gtaylor@tnetconsulting.net> - 2021-04-23 20:08 -0600
        Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-23 20:40 -0700
      Re: MSDOS 3.2 COM ports Grant Taylor <gtaylor@tnetconsulting.net> - 2021-04-23 20:14 -0600
      Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-04-24 10:07 +0200
        Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-24 15:04 -0700
          Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-04-25 10:32 +0200
            Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-26 01:32 -0700
              Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-04-26 11:42 +0200
                Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-26 04:42 -0700
                Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-04-26 14:54 +0200
                Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-26 14:10 -0700
                Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-04-27 11:40 +0200
                Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-04-27 03:56 -0700
                Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-05-01 21:56 +0200
                Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-05-01 14:36 -0700
                Re: MSDOS 3.2 COM ports "R.Wieser" <address@not.available> - 2021-05-02 10:29 +0200
                Re: MSDOS 3.2 COM ports "muta...@gmail.com" <mutazilah@gmail.com> - 2021-05-02 02:14 -0700
    Re: MSDOS 3.2 COM ports Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2021-04-28 14:15 +1000

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