Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!swrinde!ucsd!ucbvax!IFI.UIO.NO!ingea From: ingea@IFI.UIO.NO (Inge Arnesen) Newsgroups: comp.windows.ms Subject: Serial routines in Windows 3.0 Message-ID: Date: 14 Sep 90 16:53:09 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 30 X-Unparsable-Date: Fri, 14 Sep 90 18:52:32 MET DST The RS 232 support routines in Windows (OpenComm, ReadComm and so on) seems to be very slow. When running a terminal emulator using these rutines at 9600 or 19200 baud, the effective baudrate is just around 3000 - 4000 baud. The Windows utility "Terminal" is even worse. Some of this is caused by the slow scrolling of text in graphic based environments, but we have the same emulator running using a specially written COM: device driver in real mode, and the effective baudrate increases to about 7000 baud. The test results looks like this: Using COM: device driver from real mode Windows 3: 7000 baud Using Windows 3.0 comms routinmes from real mode : 4000 baud Using Windows 3.0 routines from standard mode : 3400 baud Using Windows 3.0 routines from enhanced mode : 3100 baud Using COM: device driver from enhanced mode : 4000 baud (the last oone with COMboosttime=10 ms) The COM: device driver cannot be used from standard mode on a 286, since the switch from protected to real mode takes several milliseconds, making the PC loose several characters coming in from the line. Why on earth are the Windows serial routines so slow, even in real mode ??? What can be done about it (don't ask me to write a compatible virtual device driver:-) Inge (BoB) { ingea@ifi.uio.no } ========================================================================= == Inge Arnesen, University of Oslo, Norway. == == ==