🚀 go-pugleaf

Apparently, there is a way to set the baud rate for the serial ports from
inside MacPascal.  Scott Gillespie from Reed College sent me some code
written by Mike Byrne of THINK Technologies, Inc. that uses the builtin 
procedure Generic to access the ROM serial driver.  There's no mention of 
Generic in the MacPascal documentation, so don't bother looking.

Here's a program that does nothing but set the modem line baud rate to
1200:

{HowToSetBaudRate will open the mode serialPort (serialA)}
{using the default settings (300 baud). A control call is done}
{to change the characteristics to a different baud. The ROM based}
{serial driver only supports _CONTROL calls to the output ports.}

program HowToSetBaudRate;
 const
  AOut = -7;{RefNum of serial output serialPort A}
  Control = $A004;{Trap Number of _Control}
  SetSCC = 8;{Reset SCC Channel}
  FastBaud = $CC5E;{BD is 600 baud, 8 data bits, 2 stop and no parity bit}
{5E is 1200 baud, 17C is 300 baud}
 type
  ParamBlk = record
    IOLink : LongInt;{queue link in header}
    IOType : Integer;{type byte for safety check}
    IOTrap : Integer;{FS: the Trap}
    IOCmdAddr : LongInt;{FS: Address to dispatch}
    IOCompletion : LongInt;{pointer to IOCompletion routine}
    IOResult : Integer;{IO result code}
    IOFileName : LongInt;{file name pointer}
    IOVRefNum : Integer;{refnum}
    IORefNum : Integer;{reference number for I/O operation}
    IOFileType : Integer;{Type and permission access}
    IONewType : Integer;{baud rate etc.}
   end;
 var
  serialPort : text; {Port to transmit data over}
  regs : record
    a0 : ^ParamBlk;
    a1, a2, a3, a4 : LongInt;
    d0, d1, d2, d3, d4, d5, d6, d7 : LongInt;
   end;
  ParamBlock : ParamBlk;

begin
 open(serialPort, 'modem:');{Open the serial port with default settings}
 ParamBlock.IOCompletion := 0;
 ParamBlock.IORefNum := AOut;
 ParamBlock.IOFileType := SetSCC;
 ParamBlock.IONewType := FastBaud;
 Regs.A0 := @ParamBlock;{A0 pointer to Parameter Block}
 Generic(Control, Regs);{Change the baud rate}
 if Regs.D0 <> 0 then
  writeln('Serial Port B error: ', Regs.D0);{Error codes returned in D0}

{Use the serial port}

 close(serialPort);
end. {of HowToSetBaudRate}


That's it.  I hope this helps someone.  

                                     Jerry Parrish
                                     parrish@dartmouth.CSNET