Hi Colin,

In your message of 05 Jan (11:29 hrs) to All, you wrote:

 CU> I am having trouble with my com routine..
 CU> I am using a PCCOM 4-port serial card and this unit works with a 
 CU> small test
 CU> program but when I use it in a larger program (executable approx 
 CU> 48k) I only
 CU> get some of the characters from the port.

When you say "I only get some characters" do you mean that 1) you
get ALL the characters up to a point in time then NO characters from then
on, or 2) you get the characters intermittently (eg 1234567890 is sent in
the com port but the software sees 135679) ?

 CU> The serial card is 16450 based with int vector at $02BF..
 CU> I have done very little interrupt programming so I don't know if 
 CU> that is the
 CU> problem.

It has been a few years (1991) since I've played with this multiport board.
I had a quick look through your code but didn't notice anything glaringly
obvious. I did notice a couple of weird things though.

In the InitInter routine you appear to enable the interrupts (Port[$02Bf]
:= $FF) on the multiport board prior to setting the interrupt vector. This
could cause you a problem - in my code I have the enable interrupt after
the setting of the PIC, also I do "Port[$02BF] := $80" to enable
the interrupts (I have no idea what the other 7 bits do).

 CU> procedure InitInter;
 CU>            begin
 CU>            InitPort (0);
 CU>            InitPort (1);
 CU>            InitPort (2);
 CU>            InitPort (3);
 CU>                Port[$02BF]:=$ff;
 CU>                GetIntVec(COM_IRQ_vector, OldInt0Dh);
 CU>                SetIntVec(COM_IRQ_vector, {at}Async_ISR);
 CU>                COM_mask := (1 shl (COM_IRQ_number)) xor $00FF;
 CU>                OldPic:=Port[$21];
 CU>                Port[$21] := OldPIC and COM_mask;
 CU>            end;

What are the "COM_tt := Port[BaseAddr[Serial_IOPort]+n]" lines in
the InitPort and TerminateInter routines for? Are they necessary???

 CU> procedure TerminateInter;
 CU>           var Serial_IOPort,com_tt:byte;
 CU>           begin
 CU> {             COM_mask := 1 shl (COM_IRQ_number);}
 CU>              SetIntVec(COM_IRQ_vector, OldInt0Dh);
 CU>           for Serial_IOPort := 0 to 3 do begin
 CU>                    { set Interrupt enable off }
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+1];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+2];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+3];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+4];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+5];
 CU>           COM_tt:=Port[BaseAddr[Serial_IOPort]+6];
 CU>           Port[BaseAddr[Serial_IOPort]]:=0;
 CU>           Port[BaseAddr[Serial_IOPort]+$01]:= $00;
 CU>              Port[$21] := Port[$21] and OldPIC;
 CU>           end;
 CU>              END;


Michael


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