Disable FIFO

My serial port on an old notebook uses the FIFO-Mode. What I need to do is to disable this. I expect this is a MS-DOS configuration task, but first I found no DOS-Topic anymore and second my programm runs under win3.11.
Thanks
mkdjoAsked:
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My name is MudSystems EngineerCommented:
The FIFO feature is the way the UART handles the data that Recieve/Send, So unless your UART can be shifted from this mode to what ever mode you want (LIFO pipe), it may be changeable in the BIOS Setup, in the other hand since you have installed Win3.x, i might say that you have an old PC, in which case i think is not posible, unless you provide the PC with a new Disk Controller...

Now why do you wanna changed in the first place???
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mkdjoAuthor Commented:
Because I want to use an external peripheral device which recommends no FIFO port. I don't know if it expects LIFO. It is an old notebook, which I don't know the ports too. But I expect it uses the UART 16550,  which I expect to use more modes.
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SunBowCommented:
Very interesting, modern UART w/old DOS/WIN.  Have you tried Win 95.
I don't mean for your program, I know a few who remain happy with 3.1.
I am thinking of terminology and help, where someone describing (in a help function) how Win95 does it to use phrases like:

"This feature for handling FIFO works just as good, and the same as the DOS command of
 __________________"

Like you may try using new O/S info to give you clue how the older one did it.

Another possible, considering that the modem mfrs care about them working, they may have info on properly setting/resetting this using DOS.  Anyone out there with a big modem book on hand, feel free to give this a shot.
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SunBowCommented:
Surfers,
Also consider looking at programs, like terminal emulators (aka VT100, or those targetted to BBS), that like running DOS (speed/control/price) and need these DOS configuration options.
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mkdjoAuthor Commented:
I have deleted DOS and installed W95. Now it works fine. Only installing W95 over DOS does not solve this problem.  Now it is only a theoretical question, but I still want to know how to disable it.
SunBow, I will look how W95 deactivates the FIFO. Maybe this will help to know.
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mkdjoAuthor Commented:
Tried to look at a different way. A colleague wrote a program with pascal to disable the fifo.

program setfifo;
const com_adr : array [1..4] of word = ($3f8,$2f8,$3e8,$2e8);
var portnr, state, result : integer;

procedure fifoOnOff (comport ,state : integer);
begin
  port[com_adr[comport]+2] := state and 1;
end;
begin
  if (ParamCount <> 2) then begin
    writeln ('SETFIFO: Enable/Disable FIFO-Mode of UART');
    writeln ('Call: setfifo <COM-Nr> <0|1>');
    exit;
  end;
  val(ParamStr(1),portnr,result);
  val(ParamStr(2),state,result);
  fifoonoff (portnr,state);

You took me to the right way SunBow. Thank you very much, and please post it as an answer.
end.
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SunBowCommented:
I believe if you like a comment, you can now accept is as answer.  I still have to post my own Q's to find out.

In Win95, most recommendations on use of its TAPI that include the UART issue, also recommend for 16550 setting receive and transmit buffers to high (14/16), ensure handshaking flow control is harware, and to pump the BPS up as high as you can, like to 115200.

Some equipment and WANs cannot handle, so this is no sure thing, just other ways to improve speed if you can control the environment.  External modems for example, may not keep up as well as internal ones.

I'd be interested in interaction between your pgm & Winxx, if they behave well, or if Win just assumes there've been no changes since booting it.  I ran some VB once and it did not produce same results as TAPI.  That could have been just me.
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mkdjoAuthor Commented:
There is no button to graduate a comment, at least I can't see one. I will look how this is possible.

I don't  know the interaction with windows. Looks like my windows accepted this command, even DOS accept this command. (on a different old notebook)
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mkdjoAuthor Commented:
There is the botton. Thank you very much.
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