This is a digital reproduction of book published by Bell Labs containing a number of articles from 1949 to 1951 that detail most aspects of the No. 5 Crossbar. The articles were all publised in the Bell Laboratories Record.

The entire book is 150 pages. Due to the large number of images the book is presented with each article in a separate PDF. This makes the file sizes more maneageable. A full list of files may be found here.

No. 5 Crossbar

0. Cover and Contents (3.6 MB)
1. No. 5 Crossbar - Introduction (148 KB)
2. No. 5 Crossbar - A Pictoral Summary (14.4 MB)
3. Design Patterns for No. 5 Crossbar (1.9 MB)
4. Trunking Plan for No. 5 Crossbar (1.3 MB)
5. No. 5 Crossbar Marker (300 KB)
6. Equipment Arrangements for No. 5 Crossbar Markers (1.9 MB)
7. No. 5 Crossbar Frames (3.7 MB)
8. The Originating Dial Pulse Register Circuit for the No. 5 Crossbar System (344 KB)
9. Trunk Selection by No. 5 Crossbar Markers (1.5 MB)
10. Traffic Distribution in the No. 5 Crossbar Marker (1.3 MB)
11. Connectors for the No. 5 Crossbar System (2.4 MB)
12. Senders for No. 5 Crossbar (2.7 MB)
13. Sender Link Frames for No. 5 Crossbar (1.9 MB)
14. Incoming Register Link for No. 5 Crossbar (1.1 MB)
15. Incoming Register Circuits for No. 5 Crossbar (1.8 MB)
16. Register and Sender Frames in No. 5 Crossbar (3.0 MB)
17. Number Group Frame for No. 5 Crossbar (1.9 MB)
18. Ringing Selection in No. 5 Crossbar (1.0 MB)
19. Message Register Operation in No. 5 Crossbar (1.0 MB)
20. Operator Connections in No. 5 Crossbar (184 KB)
21. Cold-Cathode-Tube Test Set (1.6 MB)
22. Maintenance Facilities for the No. 5 Crossbar System (1.0 MB)
23. The Automatic Monitor (240 KB)
24. Trouble Recording for the No. 5 Crossbar System (2.1 MB)
25. Register and Sender Testing in No. 5 Crossbar (952 KB)
26. Permanent Signals in No. 5 Crossbar (296 KB)
27. Pulse Conversion in No. 5 Crossbar (160 KB)
28. Alarm System for No. 5 Crossbar (968 KB)
29. Interoffice Transfer of Alarms in No. 5 Crossbar (252 KB)
30. No. 5 Crossbar AMA Translator (2.7 MB)
31. Pretranslation in No. 5 Crossbar (1.3 MB)
32. Traffic Registers for No. 5 Crossbar (3.1 MB)