Running UNIX V6 on an -11/23 - Revision history

Jnc: /* Switch register */ fmt

2025-06-10T09:36:42Z

‎Switch register: fmt

Jnc: /* External links */ +another one, from avitech

2022-06-02T14:56:11Z

‎External links: +another one, from avitech

Jnc: /* External links */ +1

2021-03-09T15:25:42Z

‎External links: +1

Jnc: accuracy

2021-01-23T15:09:05Z

accuracy

Jnc: NXM on no CSW

2021-01-17T20:47:05Z

NXM on no CSW

Jnc: /* Clock */ Another instance to mod

2020-10-02T09:41:39Z

‎Clock: Another instance to mod

Jnc: no clock only on KDF11-A

2019-08-14T14:39:21Z

no clock only on KDF11-A

Jnc: /* Clock */ turn off the clock only if no BDV11

2019-08-14T14:33:38Z

‎Clock: turn off the clock only if no BDV11

Jnc: Note BDV11 brain-damage

2019-08-14T14:28:59Z

Note BDV11 brain-damage

Jnc: fmt

2019-03-08T21:53:42Z

fmt

@@ Line 36: / Line 36: @@
 </pre>
-* add the following three lines to main.c (the last two go just after
+* add the following three lines to main.c (the last two go just after the check for the LTC)
 <pre>

← Older revision		Revision as of 14:56, 2 June 2022
Line 166:		Line 166:

	* [https://www.hamartun.priv.no/v6unix.html UNIX v6 on the 11/23]		* [https://www.hamartun.priv.no/v6unix.html UNIX v6 on the 11/23]
		+	* [http://avitech.com.au/?page_id=3697 UNIX V6 on QBUS PDP-11] - yet another pass at it

	[[Category: UNIX Practical Guides‎]]		[[Category: UNIX Practical Guides‎]]

@@ Line 162: / Line 162: @@
 ** [[Running Unix v6 in SIMH]]
 * [[Installing UNIX Sixth Edition on Ersatz-11]]
 [[Category: UNIX Practical Guides‎]]

@@ Line 7: / Line 7: @@
 * The ability of the /23 to have more than 256KB of [[main memory]]
-All of them are fairly simple to deal with, but they require minor modifications to the system, so you will need a running V6 to do these; bringing it up under a [[simulator]], e.g. [[Installing UNIX Sixth Edition on Ersatz-11]], is therefore required.
+All of them are fairly simple to deal with, but they require minor modifications to the system, so you will need a running V6 to do these; bringing it up under a [[simulator]], e.g. [[Installing UNIX Sixth Edition on Ersatz-11]], is therefore essentially required.
 Use the 'm40.s' [[assembly language]] file, as the [[PDP-11 Memory Management|memory management]] supported by the /23 is the same 'simple' kind (i.e. without split I+D) as that on the [[PDP-11/40]].

@@ Line 3: / Line 3: @@
 There are three issues which have to be addressed before V6 will run on a /23:
-* The lack of a [[console]] [[switch register]]
+* The lack of a [[front panel|console]] [[switch register]]
 * The lack of a [[line time clock]] [[peripheral]] (only on the [[KDF11-A CPU]]; the [[KDF11-B CPU]] has one)
 * The ability of the /23 to have more than 256KB of [[main memory]]
@@ Line 15: / Line 15: @@
 ==Switch register==
-V6 expects to see a switch register, and refers to it during [[bootstrap|booting]] to see whether to come up [[single-user]] or not.
+V6 expects to see a switch register, and refers to it during [[bootstrap|booting]] to see whether to come up [[single-user]] or not. If one is not there, the [[Central Processing Unit|CPU]] will get a 'Non-Existent Memory' [[trap|fault]].
 The best general approach is to provide a 'software switch register'; a location in low memory whose contents are used as the switch register.
@@ Line 88: / Line 88: @@
 '''''NOTE:''''' If not using the BDV11 method, it is '''critical''' to turn ''off'' the system's built-in clock (usually possible with a switch on the [[front panel]]) before and during booting, as a clock [[interrupt]] before UNIX is ready for it can trash the system (and has been observed to trash the disk, if you are really unlucky).
-'''''ALSO:''''' If using the BDV11 clock, note that once enabled, unlike all other PDP-11 [[peripheral]]s, it is not cleared by [[QBUS]] BINIT (e.g. from the RESET [[instruction]]); it must be explicitly cleared, or the machine put through a power cycle (perhaps by using the 'boot' button on the front panel).
+'''''ALSO:''''' If using the BDV11 clock, note that once enabled, unlike all other PDP-11 [[peripheral]]s, it is not cleared by [[QBUS]] BINIT (e.g. from the RESET [[instruction]]); it must be explicitly cleared, or the machine put through a power cycle (perhaps by using the 'boot' button on the front panel) to disable it.
 ==Larger main memory==
@@ Line 145: / Line 145: @@
 ==Floating point==
-The issue with floating point support is that when switching from one [[process]] to another, the [[floating point]] [[register]] contents need to be saved, and restored when returning to that process. If this is not done, the process will see 'its' floating point register contents over-written by those of any other process that uses floating point in the interim.
+The issue with floating point support is that when switching from one [[process]] to another, the [[floating point]] register contents need to be saved, and restored when returning to that process. If this is not done, the process will see 'its' floating point register contents over-written by those of any other process that uses floating point in the interim.
 This is not an issue on the -11/40, since it doesn't support floating point. However, this means that m40.s does not include the code to perform the necessary saves and restores. The necessary code is available in m45.s, though, and merely needs to be copied over.

@@ Line 83: / Line 83: @@
 		*lks = 0115;
 </pre>
 '''''NOTE:''''' If not using the BDV11 method, it is '''critical''' to turn ''off'' the system's built-in clock (usually possible with a switch on the [[front panel]]) before and during booting, as a clock [[interrupt]] before UNIX is ready for it can trash the system (and has been observed to trash the disk, if you are really unlucky).

@@ Line 4: / Line 4: @@
 * The lack of a [[console]] [[switch register]]
-* The lack (normally) of a clock [[peripheral]]
+* The lack (normally) of a [[line time clock]] [[peripheral]]
 * The ability of the /23 to have more than 256KB of [[main memory]]
@@ Line 52: / Line 52: @@
 V6 requires either a [[KW11-L Line Time Clock‏‎|KW11-L]] or [[KW11-P Programmable Real-Time Clock‏‎|KW11-P]] clock, and will 'panic' unless one or the other is found. The -11/23 does have a 60Hz clock, but... there is no control [[register]]. There are two ways to deal with this:
-# Install a [[BDV11]] card, which has a simulation of the KW11-L on it, or
+# Install a [[BDV11 Bus Terminator/ROM|BDV11]] card, which has an (imperfect; see below) simulation of the KW11-L on it, or
 # Modify the OS
@@ Line 85: / Line 85: @@
 '''''NOTE:''''' It is '''critical''' to turn ''off'' the system's built-in clock (usually possible with a switch on the console) before and during booting, as a clock [[interrupt]] before UNIX is ready for it can trash the system (and has been observed to trash the disk, if you are really unlucky).
 ==Larger main memory==

← Older revision		Revision as of 21:53, 8 March 2019
Line 1:		Line 1:
−	It is possible to run [[UNIX Sixth Edition]] on a [[PDP-11/23]], provided 'of course' that it has a [[KTF11-A memory management chip]], although this is not a model supported 'out of the box' with the Version 6 distribution.	+	It is possible to run [[UNIX Sixth Edition]] on a [[PDP-11/23]] (provided 'of course' that it has a [[KTF11-A memory management chip]]), although this is not a model supported 'out of the box' with the Version 6 distribution.

	There are three issues which have to be addressed before V6 will run on a /23:		There are three issues which have to be addressed before V6 will run on a /23: