From: address@is.invalid   
      
   JJ,   
      
   > Hardware ports are platform independent.   
      
   Indeed.   
      
   So, how do I get that baudrate bitmask onder DOS ?  the RBIL doesn't mention   
   it, even though I can easily get it under Windows. :-P   
      
   Also, most of those hardware ports seem to need device drivers, which is   
   ofcourse software and as such again platform specific.   
      
   IOW, for my question the targetted platform does seem to matter.   
      
   > Device drivers for standard serial port controllers brute force the   
   > clock divisor configuration in order to detect the acceptable baud   
   > rates against standard baud rates.   
      
   Possible, but I've got no information supporting it.   
      
   The thing is that above 128K there do not seem to be any "standard   
   baudrates".  Just do a Google for them and see what you (not) get ... :-(   
      
   I did find a list with some 128k+ baudrates.  It shows four in the 128K+ ...   
   921600 range, where the CP2102 hardware docs shows eight.  :-\   
      
   And it gets even "funnier" when you would take a look at the newer CP2104,   
   as that thing goes upto 2Mbps, and I've seen ones going upto 3Mbps.  As of   
   yet I've still have to encounter a list with standard baudrates above 921600   
   bps ...   
      
   > Yes, USB based serial port controllers could. But it won't be part of   
   > either Windows API or the serial port standards. Everything will have   
   > to be implemented as vendor-specific. e.g. custom IOCTLs.   
      
   Pray tell, how do you know it would need to be a *custom* IOCTL ?   
      
   Also, if you have a list of standard IOCTLs for serial devices I sure would   
   like to have a copy of it, as my search for "NTIoControlDeviceFile 1B0074"   
   (as executed by GetCommProperties) doesn't even return anything in regard to   
   that specific commandcode.   
      
   Having names for the different command codes would make my current   
   disassembling of the CP2102's "silabser.sys" device driver (and recognising   
   the function of each part) a lot easier.   
      
   But yes, thats pretty-much what I'm after: A way to ask the device-driver /   
   microcontroller what its extended capablilities are.    Just like   
   NTIoControlDeviceFile with the commandcode 0x1B0074 does for its basic   
   capabilities (yes, I took a peek into the GetCommProperties functions code).   
      
   > Serial port is part of the old ISA-era PC components. There's no Plug   
   > 'n Play yet in that PC era.   
      
   From my POV thats not a problem.  Just ask the device-driver/hardware if it   
   has extended capabilities, and if it responds with an "unknow request" error   
   it doesn't have any.   Simples. :-)   
      
   Regards,   
   Rudy Wieser   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)