Uses crt, dos;

Label Finish, ll00;

Const
baud = 38400;
COM=$3F8 { $2F8 };
intr=$0C { $0B };

Var
stv, srv : pointer;
cnt : word;
b : byte;
key : char;
speed_fr : word;

{----------------------------------------------------------------------------------}
{$F+}
Procedure int_1c; interrupt;
Begin
inc(cnt);
if cnt=18 then begin cnt:=0; write ('g') end;
End;
{$F-}
{-----------------------------------------------------------------------------------}
{$F+}
Procedure int_rs; interrupt;
Begin
b:=port[COM];
write (b,' ');
End;
{$F-}
{----------------------------------------------------------------------------------}

BEGIN
speed_fr:=trunc(115200/baud+0.5);
port[COM+3]:=$80; { ўЄ«. гбв ­®ўЄ бЄ®p®бвЁ }
port[COM+1]:=hi(speed_fr); port[COM+0]:=lo(speed_fr);
port[COM+3]:=$00; { 5 bit, 1 stop, parity=none }
port[COM+4]:=0;
port[COM+2]:=$03; { FIFO on }
port[COM+1]:=$01; { interrupt when rec'd data is available }

getintvec($1C,stv);
getintvec(intr,srv);

cnt:=0;
setintvec($1C,addr(int_1c));
setintvec(intr,addr(int_rs));

ll00 : if keypressed then begin
key:=readkey;
goto Finish;
end;

{ b:=port[COM+5]; }
{ if (b and $01)<>0 then begin }
{ b:=port[COM]; }
{ write (b,' '); }
{ end; }

goto ll00;

Finish :
setintvec($1C,stv);
setintvec(intr,srv);
halt;
END.

procedure Vector0C_Handler;interrupt;
begin
    .... обработка порта(ов) COM1/3

   asm
        mov al, 20h
        out 20h, al
   end
end;

port[$21] := port[$21] and $f7;

port[$20] := $20;

port[$21] := port[$21] or $10;
port[$21] := port[$21] and ($FF-$10);
port[$20] := $64;

port[$21] := port[$21] or $08;
port[$21] := port[$21] and ($FF-$08);
port[$20] := $63;