Appendix B: PC Serial Ports
Serial Ports Under Windows 3.1
Unlike the DOS-only world of yesterday, today’s multitasking environments like
Windows permit the microprocessor to communicate with up to four active
serial port devices at the same time (COM1 through COM4). For example,
under Windows, if you are using a serial mouse (on COM1 ) within a terminal
emulator program which operates a data modem (on COM2), while using a fax
board (on COM3) to transmit or receive a fax "in the background," you are
using three serial port devices simultaneously. You might even wish to make a
phone call using PassageWay Solution (on COM4) at the same time, bringing
the total up to four simultaneously active serial port devices.
The fact that Windows permits this kind of powerful multitasking does not
guarantee that the underlying PC hardware can support this level of operation,
at least without some customizing at the hardware level. Since some PCs can
support it by default (for example, those which support IRQ sharing), Windows
doesn’t prohibit you from configuring your system and attempting tasks like the
one in the previous paragraph. Unfortunately, most PCs cannot support this
operation by default and the most likely result of attempting the above
scenario is "hanging" the PC due to an IRQ conflict. On such systems, using
COM1 along with COM2 is generally fine (recall that these devices have
unique IRQs by default), but the addition of COM3 or COM4 causes the
system to fail.
Fortunately, Windows 3.1 permits complete customization of all parameters
involving serial ports through the Control Panel, including configuring
nonstandard I/O port addresses and IRQs (that is, values different from those
in the table – these parameters can be viewed and/or modified by selecting
the desired port in the Control Panel’s "Ports" applet, selecting the "Settings..."
button, then selecting the "Advanced..." button). This flexibility offers the
opportunity of salvation for owners of PCs which do not support IRQ sharing
who require the use of three or more COM ports simultaneously.
B-6
Содержание Partner 18
Страница 1: ......
Страница 15: ...Contents C Appendix C Running AT TBuzz in Export via Paste Link DDE Mode C 1 Glossary GL 1 Index Index i x ...
Страница 21: ...xvi ...
Страница 28: ...Installing and Setting Up PassageWay Solution Figure 2 1 PassageWay Solution Components 2 3 ...
Страница 65: ...Installing and Setting Up PassageWay Solution 2 40 ...
Страница 93: ...Using AT TBuzz 3 28 ...
Страница 96: ...Using AT TCall Figure 4 1 Untitled AT TCall Window 4 3 ...
Страница 97: ...Using AT TCall Figure 4 2 Components of an AT TCall Window 4 4 ...
Страница 100: ...Using AT TCall Figure 4 4 Desktop with 10 20 Quick Dials and Card Hidden 4 7 ...
Страница 101: ...Using AT TCall Figure 4 5 Desktop with 25 50 Quick Dials and Card Displayed 4 8 ...
Страница 102: ...Using AT TCall Figure 4 6 Desktop with 25 50 Quick Dials and Card Hidden 4 9 ...
Страница 144: ...Using AT TCall Figure 4 26 Printed Cards With and Without the Notes 4 51 ...
Страница 177: ...Using AT TCall 4 84 ...
Страница 181: ...Using AT TSet Figure 5 2 Components of the AT TSet Window 5 4 ...
Страница 247: ...Using Log Viewer 6 20 ...
Страница 250: ...Using AT TConnect Figure 7 1 AT TConnect Window 7 3 ...
Страница 252: ...Using AT TConnect Figure 7 2 Events Log Dialog Box 2 When finished select the OK button 7 5 ...
Страница 265: ...Using AT TConnect 7 18 ...
Страница 287: ...Troubleshooting 9 18 ...
Страница 288: ...Appendix A Menu Trees This appendix contains the menu trees for the PassageWay applications A 1 ...
Страница 289: ...Appendix A Menu Trees Figure A 1 AT TBuzz Menu Tree A 2 ...
Страница 290: ...Appendix A Menu Trees Figure A 2 AT TCall Menu Tree A 3 ...
Страница 291: ...Appendix A Menu Trees Figure A 3 AT TSet Menu Tree A 4 ...
Страница 292: ...Appendix A Menu Trees Figure A 4 Log Viewer Menu Tree A 5 ...
Страница 293: ...Appendix A Menu Trees Figure A 5 AT TConnect Menu Tree A 6 ...
Страница 305: ...Appendix B PC Serial Ports B 12 ...
Страница 311: ...Glossary GL 4 ...
Страница 318: ...560 201 103 AT T 1993 AT T ...