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

Jnc: /* Switch register */ fmt

2025-06-10T09:36:42Z

Switch register: fmt

← Older revision		Revision as of 09:36, 10 June 2025
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	</pre>		</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)
	the check for the LTC)

	<pre>		<pre>

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

2022-06-02T14:56:11Z

External links: +another one, from avitech

← Older revision		Revision as of 14:56, 2 June 2022
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	* [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]]

Jnc: /* External links */ +1

2021-03-09T15:25:42Z

External links: +1

← Older revision		Revision as of 15:25, 9 March 2021
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	** [[Running Unix v6 in SIMH]]		** [[Running Unix v6 in SIMH]]
	* [[Installing UNIX Sixth Edition on Ersatz-11]]		* [[Installing UNIX Sixth Edition on Ersatz-11]]

			==External links==

			* [https://www.hamartun.priv.no/v6unix.html UNIX v6 on the 11/23]

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

Jnc: accuracy

2021-01-23T15:09:05Z

accuracy

← Older revision		Revision as of 15:09, 23 January 2021
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	* The ability of the /23 to have more than 256KB of [[main memory]]		* 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]].		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]].

Jnc: NXM on no CSW

2021-01-17T20:47:05Z

NXM on no CSW

← Older revision		Revision as of 20:47, 17 January 2021
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	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:

	* 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 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]]		* The ability of the /23 to have more than 256KB of [[main memory]]
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	==Switch register==		==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.		The best general approach is to provide a 'software switch register'; a location in low memory whose contents are used as the switch register.
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	'''''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).		'''''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==		==Larger main memory==
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	==Floating point==		==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.		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.

Jnc: /* Clock */ Another instance to mod

2020-10-02T09:41:39Z

Clock: Another instance to mod

← Older revision		Revision as of 09:41, 2 October 2020
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	*lks = 0115;		*lks = 0115;
	</pre>		</pre>

			The identical line in clock.c should be similarly changed.

	'''''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).		'''''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).

Jnc: no clock only on KDF11-A

2019-08-14T14:39:21Z

no clock only on KDF11-A

← Older revision		Revision as of 14:39, 14 August 2019
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	* The lack of a [[console]] [[switch register]]		* The lack of a [[console]] [[switch register]]
	* The lack ~~(normally)~~ of a [[line time clock]] [[peripheral]]		* 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]]		* The ability of the /23 to have more than 256KB of [[main memory]]

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

2019-08-14T14:33:38Z

Clock: turn off the clock only if no BDV11

← Older revision		Revision as of 14:33, 14 August 2019
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	</pre>		</pre>

	'''''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).		'''''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).

	==Larger main memory==		==Larger main memory==

Jnc: Note BDV11 brain-damage

2019-08-14T14:28:59Z

Note BDV11 brain-damage

← Older revision		Revision as of 14:28, 14 August 2019
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	* The lack of a [[console]] [[switch register]]		* 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]]		* The ability of the /23 to have more than 256KB of [[main memory]]

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	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:		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		# Modify the OS

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	'''''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).		'''''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).

			'''''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]]).

	==Larger main memory==		==Larger main memory==

Jnc: fmt

2019-03-08T21:53:42Z

fmt

← 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: