UNIX Second Edition - Revision history

Jnc: Mention archaeology without kernel source

2023-10-20T01:54:54Z

Mention archaeology without kernel source

Jnc: /* External links */ +TUHS wiki link

2023-10-18T18:50:46Z

‎External links: +TUHS wiki link

Jnc: Use common man ref format

2023-10-18T17:51:53Z

Use common man ref format

Jnc: Add my archaeology

2023-10-18T17:03:28Z

Add my archaeology

Jnc: Add Matthew Gilmore's archaeology on V2 commands

2023-10-18T16:19:09Z

Add Matthew Gilmore's archaeology on V2 commands

Jnc: V2 could use the KS11

2023-05-17T22:43:35Z

V2 could use the KS11

Jnc: +previous version

2022-06-23T04:19:42Z

+previous version

Jnc: +next version

2022-05-25T00:56:57Z

+next version

Jnc: Fills the gap

2022-05-25T00:43:58Z

Fills the gap

New page

{{Infobox OS
| name = Unix V2
| creator = AT&T/[[Western Electric]]
| year introduced = June, 1972
| type = [[Multi-tasking]], [[multi-user]]
| architecture = [[PDP-11 architecture|PDP-11]]
}}

'''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. There were 10 instances of UNIX running inside Bell at this point.

It still ran on the [[PDP-11/20]] model of the PDP-11; the [[PDP-11/45]] was apparently expected in the near future. The [[file system]] is almost identical to the [[UNIX file system|V6 one]]; the only major differences are that i) the free blocks are stored as a bit [[array]], rather than a [[list]], and ii) [[peripheral|device]] 'special files' are indicated by [[inode]] numbers below 41. (not via a flag in the 'mode' word in the inode, as later).

A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] has the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands. The 'NIX Programmer's Manual: Second Edition' is also available.

==External links==

* [https://minnie.tuhs.org/cgi-bin/utree.pl?file=V2 V2]
* [http://squoze.net/UNIX/v2man/ UNIX Programmer's Manual: Second Edition]
** [http://squoze.net/UNIX/v2man/man0 Introduction]
** [http://squoze.net/UNIX/v2man/man5/fs File system]
** [http://squoze.net/UNIX/v2man/man7/bproc Boot procedures]
** [http://squoze.net/UNIX/v2man/man7/init init - process control initialization]

{{Nav Unix}}

[[Category: PDP-11 Operating Systems]]
[[Category: Non-DEC Operating Systems]]
[[Category: Unix OS's]]

@@ Line 10: / Line 10: @@
 }}
-'''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. There were 10 instances of UNIX running inside Bell at this point. It still ran on the [[PDP-11/20]] model of the PDP-11.
+'''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. The [[source code]] for the [[kernel]] has been completely lost, so it is not possible to make authoritative, detailed, statements about it; but documentation, and source for some commands still exists, which allows technological archaeologists to draw some conclusions about it.
-Support for protection (and relocation - i.e. memory that looks, to user code, as if it's at 0, but is actually at, say, 060000 in physical terms) in PDP-11 UNIX ''pre-dates'' the [[PDP-11/45]] (the first PDP-11 model on which it was a standard). [[Digital Equipment Corporation|DEC]] had a rare, and now almost forgotten "Memory Protect & Relocate" [[memory management]] option for the -11/20, the [[KS11 Memory Protection and Relocation option|KS11]]. Some of the -11/20's running V2 UNIX had a KS11 - "the current system, which has relocation and protection hardware". ([http://squoze.net/UNIX/v2man/man5/core core(V)])
+There were 10 instances of UNIX running inside Bell at this point. It still ran on the [[PDP-11/20]] model of the PDP-11.
-One big question concerns details of how the process' address space was laid out - the man pages for ld(III) and exec(II) simply say nothing at all. With the KS11, one can assume it started at 0 - but who knows? Without the KS11, it must have started at a higher address (since on the PDP-11, [[interrupt vector]]s are in low memory), as on [[MINI-UNIX#Implementation_details|MINI-UNIX]]; but again, neither V1's ld(III) nor exec(II) mentions this detail. One could work it out from the V1 [[kernel]] source, if one is ''really'' interested...
+Support for protection (and relocation - i.e. memory that looks, to user code, as if it's at 0, but is actually at, say, 060000 in physical terms) in PDP-11 UNIX actually ''pre-dates'' the later [[PDP-11/45]] (the first PDP-11 model on which it was a standard). [[Digital Equipment Corporation|DEC]] had a rare, and now almost forgotten "Memory Protect & Relocate" [[memory management]] option for the -11/20, the [[KS11 Memory Protection and Relocation option|KS11]]. Some of the -11/20's running V2 UNIX had a KS11 - "the current system, which has relocation and protection hardware". ([http://squoze.net/UNIX/v2man/man5/core core(V)])
-Some also had [[KE11-A Extended Arithmetic Element]]s. (It's important to remember that not all the machines running UNIX would have had their hardware updated simultaneously: e.g. the patent group's -11/20 would not have needed the KS11 as much, since it was running mature [[application]]s. So V2 UNIX was probably conditionalized to run with and without the KS11. V1 used the KE11-A, and was not conditionalized to be able to run without it, though.)
+One big question concerns details of how a [[process]]' [[address space]] was laid out - the man pages for ld(I) and exec(II) simply say nothing about this at all. With the KS11, one can assume it started at 0 - but who knows? Without the KS11, it must have started at a higher address (since on the PDP-11, [[interrupt vector]]s are in low memory), as on [[MINI-UNIX#Implementation_details|MINI-UNIX]]; but again, neither V1's ld(I) nor exec(II) mentions this detail. One could work it out from the V1 kernel source (which ''does'' still exist, if one is ''really'' interested...
 The -11/45 was apparently expected in the near future; V2 seems to have started looking forward to it - "a trap is simulated by the [[floating point]] simulator" ([http://squoze.net/UNIX/v2man/man5/core core(V)]); "if they correspond to 11/45 floating point [[instruction]]s". ([http://squoze.net/UNIX/v2man/man3/fptrap fptrap(III)]) It is possible that they already had the -11/45 at this point, but one would tend to doubt it: "immediate mode ((pc)+) is not supported, since the PDP-11/45 handbook is not clear on what to do about it." (If they had it, a simple experiment would have produced the answer.) And "Double precision results are probably less correct than the hardware will be" (note tense). (All from fptrap(III).)
@@ Line 24: / Line 26: @@
 ==Source==
-A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] claims to have the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands (but see below). The 'UNIX Programmer's Manual: Second Edition' is also available.
+As mentioned, a complete copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] claims to have the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands (but see below). The 'UNIX Programmer's Manual: Second Edition' is also available.
-The 'cmd' directory at TUHS actually seems to be for [[UNIX Third Edition|V3]] (see discussion there). However, the sources for some V2 commands were reconstructed by [[decompilation|decompiling]] the [[object code]] for some that were located in an old dump (in the 's2-bits.tar.gz' file in the TUHS archive, below). The binaries seem to be a mixture of 'naked' binaries, with some in V1 and V2 [[UNIX a.out file|a.out formats]].
+The 'cmd' directory at TUHS actually seems to be for [[UNIX Third Edition|V3]] (see discussion there). However, the sources for some V2 commands were reconstructed by [[decompilation|decompiling]] the [[object code]] for some that were located in an old dump (in the 's2-bits.tar.gz' file in the TUHS archive, below). The binaries seem to be a mixture of 'naked' binaries, along with some in V1 and V2 [[UNIX a.out file|a.out formats]].
 ==External links==

@@ Line 34: / Line 34: @@
 * [https://www.tuhs.org/Archive/Distributions/Research/1972_stuff 1972 stuff] - the source for the above
 ** [https://www.tuhs.org/Archive/Distributions/Research/1972_stuff/Readme Readme] - a discussion of what's there
 * [https://minnie.tuhs.org/mailman3/hyperkitty/list/tuhs@tuhs.org/thread/Y5CHHVMQY3JUOKI4PD7OVB4FBD4ILV2O/ S2-bits V2 Source Code Restoration]
 * [https://gitlab.com/segaloco/v2src v2src]

@@ Line 12: / Line 12: @@
 '''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. There were 10 instances of UNIX running inside Bell at this point. It still ran on the [[PDP-11/20]] model of the PDP-11.
-Support for protection (and relocation - i.e. memory that looks, to user code, as if it's at 0, but is actually at, say, 060000 in physical terms) in PDP-11 UNIX ''pre-dates'' the [[PDP-11/45]] (the first PDP-11 model on which it was a standard). [[Digital Equipment Corporation|DEC]] had a rare, and now almost forgotten "Memory Protect & Relocate" [[memory management]] option for the -11/20, the [[KS11 Memory Protection and Relocation option|KS11]]. Some of the -11/20's running V2 UNIX had a KS11 - "the current system, which has relocation and protection hardware" ([http://squoze.net/UNIX/v2man/man5/core core(V)]).
+Support for protection (and relocation - i.e. memory that looks, to user code, as if it's at 0, but is actually at, say, 060000 in physical terms) in PDP-11 UNIX ''pre-dates'' the [[PDP-11/45]] (the first PDP-11 model on which it was a standard). [[Digital Equipment Corporation|DEC]] had a rare, and now almost forgotten "Memory Protect & Relocate" [[memory management]] option for the -11/20, the [[KS11 Memory Protection and Relocation option|KS11]]. Some of the -11/20's running V2 UNIX had a KS11 - "the current system, which has relocation and protection hardware". ([http://squoze.net/UNIX/v2man/man5/core core(V)])
 One big question concerns details of how the process' address space was laid out - the man pages for ld(III) and exec(II) simply say nothing at all. With the KS11, one can assume it started at 0 - but who knows? Without the KS11, it must have started at a higher address (since on the PDP-11, [[interrupt vector]]s are in low memory), as on [[MINI-UNIX#Implementation_details|MINI-UNIX]]; but again, neither V1's ld(III) nor exec(II) mentions this detail. One could work it out from the V1 [[kernel]] source, if one is ''really'' interested...
@@ Line 18: / Line 18: @@
 Some also had [[KE11-A Extended Arithmetic Element]]s. (It's important to remember that not all the machines running UNIX would have had their hardware updated simultaneously: e.g. the patent group's -11/20 would not have needed the KS11 as much, since it was running mature [[application]]s. So V2 UNIX was probably conditionalized to run with and without the KS11. V1 used the KE11-A, and was not conditionalized to be able to run without it, though.)
-The -11/45 was apparently expected in the near future; V2 seems to have started looking forward to it - "a trap is simulated by the [[floating point]] simulator" ([http://squoze.net/UNIX/v2man/man5/core core(V)]); "if they correspond to 11/45 floating point [[instruction]]s" ([http://squoze.net/UNIX/v2man/man3/fptrap fptrap[III]). It is possible that they already had the -11/45 at this point, but one would tend to doubt it: "immediate mode ((pc)+) is not supported, since the PDP-11/45 handbook is not clear on what to do about it." (If they had it, a simple experiment would have produced the answer.) And "Double precision results are probably less correct than the hardware will be" (note tense). (All from fptrap[III].)
+The -11/45 was apparently expected in the near future; V2 seems to have started looking forward to it - "a trap is simulated by the [[floating point]] simulator" ([http://squoze.net/UNIX/v2man/man5/core core(V)]); "if they correspond to 11/45 floating point [[instruction]]s". ([http://squoze.net/UNIX/v2man/man3/fptrap fptrap(III)]) It is possible that they already had the -11/45 at this point, but one would tend to doubt it: "immediate mode ((pc)+) is not supported, since the PDP-11/45 handbook is not clear on what to do about it." (If they had it, a simple experiment would have produced the answer.) And "Double precision results are probably less correct than the hardware will be" (note tense). (All from fptrap(III).)
 The [[file system]] is almost identical to the [[UNIX file system|V6 one]]; the only major differences are that i) the free blocks are stored as a bit [[array]], rather than a linked [[list]], and ii) [[peripheral|device]] 'special files' are indicated by [[inode]] numbers below 41. (not via a flag in the 'mode' word in the inode, as later).
@@ Line 26: / Line 26: @@
 A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] claims to have the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands (but see below). The 'UNIX Programmer's Manual: Second Edition' is also available.
-The 'cmd' directory at TUHS actually seems to be for [[UNIX Third Edition|V3]] (see discussion there). However, the sources for some V2 commands were reconstructed by [[decompilation|decompiling]] the [[object code]] for some that were located in an old dump (in the 's2-bits.tar.gz' file in the TUHS archive, below). They seem to be a mixture of 'naked' binaries, along with some in V1 and V2 [[UNIX a.out file|a.out
+The 'cmd' directory at TUHS actually seems to be for [[UNIX Third Edition|V3]] (see discussion there). However, the sources for some V2 commands were reconstructed by [[decompilation|decompiling]] the [[object code]] for some that were located in an old dump (in the 's2-bits.tar.gz' file in the TUHS archive, below). The binaries seem to be a mixture of 'naked' binaries, with some in V1 and V2 [[UNIX a.out file|a.out formats]].
 ==External links==

@@ Line 10: / Line 10: @@
 }}
-'''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. There were 10 instances of UNIX running inside Bell at this point.
+'''UNIX Second Edition''' (often referred to as '''UNIX V2''' or '''V2 UNIX''' - 'Unix' was still normally given in all capital letters at this point in time) was an early version of [[UNIX]]. There were 10 instances of UNIX running inside Bell at this point. It still ran on the [[PDP-11/20]] model of the PDP-11.
-It still ran on the [[PDP-11/20]] model of the PDP-11; the [[PDP-11/45]] was apparently expected in the near future. Some of the -11/20's running UNIX had a [[KS11 Memory Protection and Relocation option]] to provide [[memory management]] ("the current system, which has relocation and protection hardware"([http://squoze.net/UNIX/v2man/man5/core core(V)])). Some also had [[KE11-A Extended Arithmetic Element]]s.
+Support for protection (and relocation - i.e. memory that looks, to user code, as if it's at 0, but is actually at, say, 060000 in physical terms) in PDP-11 UNIX ''pre-dates'' the [[PDP-11/45]] (the first PDP-11 model on which it was a standard). [[Digital Equipment Corporation|DEC]] had a rare, and now almost forgotten "Memory Protect & Relocate" [[memory management]] option for the -11/20, the [[KS11 Memory Protection and Relocation option|KS11]]. Some of the -11/20's running V2 UNIX had a KS11 - "the current system, which has relocation and protection hardware" ([http://squoze.net/UNIX/v2man/man5/core core(V)]).
 The [[file system]] is almost identical to the [[UNIX file system|V6 one]]; the only major differences are that i) the free blocks are stored as a bit [[array]], rather than a linked [[list]], and ii) [[peripheral|device]] 'special files' are indicated by [[inode]] numbers below 41. (not via a flag in the 'mode' word in the inode, as later).

@@ Line 16: / Line 16: @@
 The [[file system]] is almost identical to the [[UNIX file system|V6 one]]; the only major differences are that i) the free blocks are stored as a bit [[array]], rather than a linked [[list]], and ii) [[peripheral|device]] 'special files' are indicated by [[inode]] numbers below 41. (not via a flag in the 'mode' word in the inode, as later).
-A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] has the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands. The 'UNIX Programmer's Manual: Second Edition' is also available.
+==Source==
 ==External links==
 * [https://minnie.tuhs.org/cgi-bin/utree.pl?file=V2 V2] - file tree at TUHS
 * [http://squoze.net/UNIX/v2man/ UNIX Programmer's Manual: Second Edition]
 ** [http://squoze.net/UNIX/v2man/man0 Introduction]

@@ Line 3: / Line 3: @@
 | creator = AT&T/[[Western Electric]]
 | year introduced = June, 1972
-| next version = [[UNIX Third Edition]]
+| previous version = [[UNIX First Edition|V1]]
 | type = [[Multi-tasking]], [[multi-user]]
 | architecture = [[PDP-11 architecture|PDP-11]]
@@ Line 12: / Line 14: @@
 It still ran on the [[PDP-11/20]] model of the PDP-11; the [[PDP-11/45]] was apparently expected in the near future. The [[file system]] is almost identical to the [[UNIX file system|V6 one]]; the only major differences are that i) the free blocks are stored as a bit [[array]], rather than a [[list]], and ii) [[peripheral|device]] 'special files' are indicated by [[inode]] numbers below 41. (not via a flag in the 'mode' word in the inode, as later).
-A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] has the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands. The 'NIX Programmer's Manual: Second Edition' is also available.
+A copy of Second Edition does not seem to be extant. [[The Unix Heritage Society|TUHS]] has the [[source code]] for some of its user code: an early version of the first [[C programming language|C]] [[compiler]] (C was just being defined at the point in time), and many commands. The 'UNIX Programmer's Manual: Second Edition' is also available.
 ==External links==
-* [https://minnie.tuhs.org/cgi-bin/utree.pl?file=V2 V2]
+* [https://minnie.tuhs.org/cgi-bin/utree.pl?file=V2 V2] - file tree at TUHS
 * [http://squoze.net/UNIX/v2man/ UNIX Programmer's Manual: Second Edition]
 ** [http://squoze.net/UNIX/v2man/man0 Introduction]