The UNIX system family tree: Research and BSD

First Edition (V1)
     |
Second Edition (V2)
     |
Third Edition (V3)
     |
Fourth Edition (V4)
     |
Fifth Edition (V5)
     |
Sixth Edition (V6) -----*
       /                |
        /               |
         /              |
Seventh Edition (V7)    |
            /           |
             /        1BSD
             32V        |
               /      2BSD---------------*
                /    /                   |
                 /  /                    |
                  //                     |
                 3BSD                    |
                  |                      |
               4.0BSD               2.7.9BSD
                  |                      |
               4.1BSD --------------> 2.8BSD
                  |                      |
              4.1aBSD -----------/       |
                  |                /     |
              4.1bBSD                /   |
                  |                    / |
      *------ 4.1cBSD --------------> 2.9BSD
     /            |                      |
Eighth Edition    |                   2.9BSD-Seismo
     |            |                      |
     +----<--- 4.2BSD               2.9.1BSD
     |            |                      |
     +----<--- 4.3BSD -------------> 2.10BSD
     |            |               /      |
Ninth Edition     |              / 2.10.1BSD
     |         4.3BSD Tahoe-----+        |
     |            |              /       |
     |            |                /     |
     v            |                  2.11BSD
Tenth Edition     |                      |
                  |                  2.11BSD rev #430
               4.3BSD NET/1              |
                  |                      v
               4.3BSD Reno
                  |
   *---------- 4.3BSD NET/2 -------------------+-------------*
   |                    |                      |             |
386BSD 0.0              |                      |           BSD/386 ALPHA
   |                    |                      |             |
386BSD 0.1 ------------>+                      |           BSD/386 0.3.[13]
   |     /              |                  4.4BSD Alpha      |
   |     386BSD 1.0     |                      |           BSD/386 0.9.[34]
   |                    |                  4.4BSD            |
   |                    |                    / |             |
   |                    |   4.4BSD-Encumbered  |             |
   |                 NetBSD 0.8                |           BSD/386 1.0
   |                    |                      |             |
FreeBSD 1.0          NetBSD 0.9                |           BSD/386 1.1
   |                    |           .----- 4.4BSD Lite       |
FreeBSD 1.1             |          /   /       |     /       |
   |                    |         /   /        |      /      |
FreeBSD 1.1.5       .---|--------'   /         |       /     |
   |               /    |           /          |        /    |
FreeBSD 1.1.5.1   /     |          /           |         /   |
   |             /   NetBSD 1.0 <-'            |          /  |
   |            /       |                      |           / |
FreeBSD 2.0 <--'        |                      |           BSD/OS 2.0
   |                     /                     |             |
FreeBSD 2.0.5             /                    |           BSD/OS 2.0.1
   |                 .-----/------------- 4.4BSD Lite2       |
   |                 |      /             |  |   |   |       |
   |                 | .-----|------Rhapsody |   |   |       |
   |                 | |     |        NetBSD 1.3 |   |       |
   |                 | |     |           OpenBSD 2.3 |       |
   |                 | |     |                BSD/OS 3.0     |
FreeBSD 2.1          | |     |                               |
|   |               | |  NetBSD 1.1 ------.               BSD/OS 2.1
| FreeBSD 2.1.5     | |     |              /                |
|     |             | |  NetBSD 1.2         /             BSD/OS 3.0
| FreeBSD 2.1.6     | |     |  /          OpenBSD 2.0       |
|     |             | |     |   /             |             |
| FreeBSD 2.1.6.1   | |     |    /            |             |
|     |             | |     |     /           |             |
| FreeBSD 2.1.7     | |     |      |          |             |
|     |             | |     |  NetBSD 1.2.1   |             |
| FreeBSD 2.1.7.1   | |     |                 |             |
|                   | |     |                 |             |
|                   | |     |                 |             |
*-FreeBSD 2.2       | |     |                 |             |
|        /          | |     |                 |             |
|     FreeBSD 2.2.1 | |     |                 |             |
|         |         | |     |                 |             |
|     FreeBSD 2.2.2 | |     |             OpenBSD 2.1       |
|         |         | |     |                 |             |
|     FreeBSD 2.2.5 | |     |                 |             |
|         |         | |     |             OpenBSD 2.2       |
|         |         | |  NetBSD 1.3           |             |
|     FreeBSD 2.2.6 | |     |    |            |             |
|         |         | |     | NetBSD 1.3.1    |           BSD/OS 3.1
|         |         | |     |    |        OpenBSD 2.3       |
|         |         | |     | NetBSD 1.3.2    |             |
|     FreeBSD 2.2.7 | |     |    |            |             |
|         |         | |     |    |            |           BSD/OS 4.0
|         v         | |     |    |            |             |
|     FreeBSD 2.2.8 | |     |    |            |             |
|                   | |     |    |        OpenBSD 2.4       |
FreeBSD 3.0 <--------* |     |    v            |             |
|                     |     | NetBSD 1.3.3    |             |
*---FreeBSD 3.1       |     |                 |             |
|       |             |     |                 |           BSD/OS 4.0.1
|   FreeBSD 3.2----*  |  NetBSD 1.4       OpenBSD 2.5       |
|       |          |  |  |  |    |            |             |
|       |          |  |  |  |    |            |             |
|       |          |  |  |  |    |            |             |
|   FreeBSD 3.3    |  |  |  | NetBSD 1.4.1    |             |
|       |          |  |  |  |    |        OpenBSD 2.6       |
|   FreeBSD 3.4    |  |  |  |    |            |             |
|           |      |  |  |  |    |            |           BSD/OS 4.1
FreeBSD 4.0  |      |  |  |  | NetBSD 1.4.2    |             |
|           |      |  |  |  |    |            |             |
|           |      |  |  |  |    |            |             |
|   FreeBSD 3.5    |  |  |  |    |        OpenBSD 2.7       |
|           |      |  |  |  |    |            |             |
|   FreeBSD 3.5.1  |  |  |  |    |            |             |
|                  |  |  |  |    |            |             |
*---FreeBSD 4.1    |  |  |  |    |            |             |
|      |           |  | (?) |    |            |             |
|   FreeBSD 4.1.1  |  |  /  |    |            |             |
|      |           |  | /   |    |            |             |
|   FreeBSD 4.2   Darwin/   | NetBSD 1.4.3    |             |
|      |         Mac OS X   |    |        OpenBSD 2.8     BSD/OS 4.2
|      |             |      |    v            |             |
|      |             |      |                 |             |
|      |           10.0  NetBSD 1.5           |             |
|   FreeBSD 4.3      |      |    |            |             |
|      |             |      |    |        OpenBSD 2.9       |
|      |             |      | NetBSD 1.5.1    |             |
|      |             |      |    |            |             |
|   FreeBSD 4.4-.    |      | NetBSD 1.5.2    |             |
|      |        | Mac OS X  |    |            |             |
|      |        |   10.1    |    |        OpenBSD 3.0       |
|   FreeBSD 4.5 |    |      |    |            |             |
|      |         /   |      |    |            |           BSD/OS 4.3
|   FreeBSD 4.6   /  |      |    |        OpenBSD 3.1       |
|      |           / |      | NetBSD 1.5.3    |            |
|   FreeBSD 4.6.2 Mac OS X  |    |            |             |
|      |            10.2    |    v            |             |
|   FreeBSD 4.7      |      |                 |             |
|      |             |   NetBSD 1.6       OpenBSD 3.2       |
|   FreeBSD 4.8      |      |    |            |             |
|      |             |      | NetBSD 1.6.1    |             |
|      |             |      |    |        OpenBSD 3.3       |
|      |             |      |    |            |             |
|   FreeBSD 4.9      |      |    |        OpenBSD 3.4       |
|      |             |      |    |            |             |
|      v             |      |    |            |             |
|                    |      |    v            |             |
FreeBSD 5.0       |      |                 |             |
|                    |      |                 |            BSD/OS 5.0
FreeBSD 5.1           |   NetBSD -current  OpenBSD -current  |
|          /         |      |                 |             v
|           ----- Mac OS X  |                 |
|                   10.3    |                 |
FreeBSD 5 -current    |      |                 |
|                    |      |                 |
v                    v      v                 v