Hardware manual

Table of Contents
Serial HOWTO
11.5 What is isapnp ?.............................................................................................................................51
11.6 Connecting two PCs together via serial ports................................................................................51
11.7 Connect the serial port to a fast network: ser2net..........................................................................51
12. Speed (Flow Rate)...........................................................................................................................52
12.1 Very High Speeds.........................................................................................................................52
Speeds over 115.2kbps....................................................................................................................52
How speed is set in hardware: the divisor and baud_base.............................................................52
Setting the divisor, speed accounting..............................................................................................53
Crystal frequency is higher than baud_base....................................................................................53
12.2 Higher Serial Throughput.............................................................................................................53
13. Locking Out Others..........................................................................................................................54
13.1 Introduction....................................................................................................................................54
13.2 Lock-Files.....................................................................................................................................54
13.3 Change Owners, Groups, and/or Permissions of Device Files......................................................55
14. Serial Communications Programs And Utilities.............................................................................55
14.1 List of Software..............................................................................................................................55
14.2 kermit and zmodem........................................................................................................................56
15. Serial Tips And Miscellany.............................................................................................................56
15.1 Serial Modules..............................................................................................................................56
15.2 Kernel Configuration....................................................................................................................57
15.3 Number of Serial Ports Supported................................................................................................57
15.4 Serial Console (console on the serial port)....................................................................................57
15.5 Line Drivers...................................................................................................................................57
15.6 Stopping the Data Flow when Printing, etc...................................................................................57
15.7 Known IO Address Conflicts.........................................................................................................57
Avoiding IO Address Conflicts with Certain Video Boards..........................................................58
IO address conflict with ide2 hard drive.........................................................................................58
15.8 Known Defective Hardware..........................................................................................................58
Problem with AMD Elan SC400 CPU (PC-on-a-chip)...................................................................58
16. Troubleshooting..............................................................................................................................58
16.1 Serial Electrical Test Equipment..................................................................................................58
Breakout Gadgets, etc......................................................................................................................58
Measuring voltages..........................................................................................................................59
Taste voltage....................................................................................................................................59
16.2 Serial Monitoring/Diagnostics.......................................................................................................59
16.3 (The following subsections are in both the Serial and Modem HOWTOs)...................................59
16.4 Serial Port Can't be Found............................................................................................................59
Scanning/probing legacy ports........................................................................................................60
16.5 Linux Creates an Interrupt Conflict (your PC has an ISA slot).....................................................60
16.6 Extremely Slow: Text appears on the screen slowly after long delays.........................................60
16.7 Somewhat Slow: I expected it to be a few times faster.................................................................61
16.8 The Startup Screen Shows Wrong IRQs for the Serial Ports........................................................61
16.9 "Cannot open /dev/ttyS?: Device or resource busy.......................................................................61
16.10 "Cannot open /dev/ttyS?: Permission denied".............................................................................61
16.11 "Cannot open /dev/ttyS?".............................................................................................................62
16.12 "Operation not supported by device" for ttyS?............................................................................62
16.13 "Cannot create lockfile. Sorry"...................................................................................................62
Serial HOWTO
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