PDP-11/20 - Revision history

Jnc: /* Extensions */ Update Bell Labs URLs (blast Nokia)

2025-06-30T20:11:02Z

Extensions: Update Bell Labs URLs (blast Nokia)

← Older revision		Revision as of 20:11, 30 June 2025
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	One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.		One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.

	The [[KS11 Memory Protection and Relocation option\|KS11]] was apparently DEC's first attempt at an add-on to provide memory management to the -11/20. Other than a [https://www.bell-labs~~.com~~/~~usr~~/~~dmr/www~~/odd.html funny story], little is known of it. The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.		The [[KS11 Memory Protection and Relocation option\|KS11]] was apparently DEC's first attempt at an add-on to provide memory management to the -11/20. Other than a [https://www.nokia.com/bell-labs/about/dennis-m-ritchie/odd.html funny story], little is known of it. The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it also allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.

	==Software==		==Software==

Jnc: /* External links */ +pdp11/20 Price List

2024-10-11T21:22:38Z

External links: +pdp11/20 Price List

← Older revision		Revision as of 21:22, 11 October 2024
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	==External links==		==External links==

			* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Price-List_19691215.pdf pdp11 price list] (December 15, 1969) - pre-production price list, includes the 'PDP-11/10'
			* [http://www.bitsavers.org/pdf/dec/pdp11/1120/PDP11-20_Price_List_19701101.pdf pdp11/20 Price List] (November 1, 1970)
	* [http://www.bitsavers.org/pdf/dec/pdp11/1120/ 11/20] - documentation at [[Bitsavers]]		* [http://www.bitsavers.org/pdf/dec/pdp11/1120/ 11/20] - documentation at [[Bitsavers]]
	** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemManual.pdf PDP-11/20 system manual] (DEC-11-HR1B-D)		** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemManual.pdf PDP-11/20 system manual] (DEC-11-HR1B-D)
	** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]		** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]
	* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook		* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook
	* [http://vintagecomputer.net/digital/PDP11-20/PDP11_Price-List_19691215.pdf pdp11 price list] - pre-production price list, includes the 'PDP-11/10'
	* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Brochure_1970Feb.pdf pdp11] - DEC brochure		* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Brochure_1970Feb.pdf pdp11] - DEC brochure
	* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Articles_1970Jan.pdf PDP-11 rides on a unibus] - announcement press coverage		* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Articles_1970Jan.pdf PDP-11 rides on a unibus] - announcement press coverage

Jnc: /* External links */ +original documents

2023-12-31T17:27:48Z

External links: +original documents

← Older revision		Revision as of 17:27, 31 December 2023
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	** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]		** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]
	* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook		* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook
			* [http://vintagecomputer.net/digital/PDP11-20/PDP11_Price-List_19691215.pdf pdp11 price list] - pre-production price list, includes the 'PDP-11/10'
			* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Brochure_1970Feb.pdf pdp11] - DEC brochure
			* [https://vintagecomputer.net/digital/PDP11-20/PDP11_Articles_1970Jan.pdf PDP-11 rides on a unibus] - announcement press coverage
	* [http://hampage.hu/pdp-11/1120.html PDP-11/20, /15]		* [http://hampage.hu/pdp-11/1120.html PDP-11/20, /15]

Jnc: Fill out infobox

2023-12-31T16:17:41Z

Fill out infobox

← Older revision		Revision as of 16:17, 31 December 2023
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	\| name = PDP-11/20		\| name = PDP-11/20
	\| manufacturer = [[Digital Equipment Corporation]]		\| manufacturer = [[Digital Equipment Corporation]]
	\| ~~introduced~~= 1970		\| architecture = [[PDP-11]]
	\| bus arch = [[UNIBUS]]		\| year announced = January, 1970
			\| year design started = before January, 1969
			\| year first shipped = June, 1970
			<!-- \| year discontinued = -->
			\| form factor = [[Minicomputer]]
			\| word size = 16
			\| physical address = 256KB (only 56KB accessible by basic -11/20)
			\| virtual address = 64KB
			\| logic type = [[transistor-transistor logic\|TTL]]
			\| design type = [[state machine]] (not [[microcode]]d)
			\| clock speed = 280 nsec
			<!-- \| cycle time = CPU cycle time in ns/µs/etc -->
			\| instruction speed = 2.3 μsec (register-register)
			\| memory speed = [[MM11-E and MM1-F core memories\|MM11-E]]: 500 nsec [[access time]]<br>      1.2 μsec [[cycle time]]
			\| cpu = [[KA11 CPU]]
			\| bus arch = [[UNIBUS]]
			\| memory mgmt = none standard
			\| operating system = [[DOS-11]], [[DOS/BATCH]], [[RSTS-11]], [[UNIX]], others
			\| predecessor = none
			\| successor = [[PDP-11/05]]
	}}		}}
	[[Image:PDP11-20.jpg\|~~right~~\|~~150px~~\|thumb\|PDP11/20]]		[[Image:PDP11-20.jpg\|left\|200px\|thumb\|PDP11/20]]

	The PDP-11/20 was the first [[PDP-11]] from [[Digital Equipment Corporation\|DEC]]; its [[KA11 CPU]] was built from a set of [[DEC card form factor\|quad width extended-length]] cards carrying SSI [[transistor-transistor logic\|TTL]] [[integrated circuit\|chips]], along with a few dual width cards. It introduced the [[UNIBUS]] as a universal path to connect together the [[Central Processing Unit\|CPU]], [[main memory]] and [[peripheral\|devices]].		The PDP-11/20 was the first [[PDP-11]] from [[Digital Equipment Corporation\|DEC]]; its [[KA11 CPU]] was built from a set of [[DEC card form factor\|quad width extended-length]] cards carrying SSI [[transistor-transistor logic\|TTL]] [[integrated circuit\|chips]], along with a few dual width cards. It introduced the [[UNIBUS]] as a universal path to connect together the [[Central Processing Unit\|CPU]], [[main memory]] and [[peripheral\|devices]].
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	One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.		One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.

	The KS11 was apparently DEC's first attempt at an add-on to provide memory management to the -11/20. Other than a [https://www.bell-labs.com/usr/dmr/www/odd.html funny story], ~~nothing~~ is known of it. The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.		The [[KS11 Memory Protection and Relocation option\|KS11]] was apparently DEC's first attempt at an add-on to provide memory management to the -11/20. Other than a [https://www.bell-labs.com/usr/dmr/www/odd.html funny story], little is known of it. The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.

	==Software==		==Software==

Jnc: /* External links */ +http://hampage.hu/pdp-11/1120.html

2023-09-22T17:00:51Z

External links: +http://hampage.hu/pdp-11/1120.html

← Older revision		Revision as of 17:00, 22 September 2023
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	** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]		** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]
	* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook		* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook
			* [http://hampage.hu/pdp-11/1120.html PDP-11/20, /15]

	{{PDP-11}}		{{PDP-11}}

	[[Category: UNIBUS PDP-11s]]		[[Category: UNIBUS PDP-11s]]

Jnc: /* See also */ +KS11 Memory Protection and Relocation option

2023-06-30T00:46:34Z

See also: +KS11 Memory Protection and Relocation option

← Older revision		Revision as of 00:46, 30 June 2023
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	Trivia: The machine was set to be named "PDP-11/30" originally, but it was renamed to 11/20 because of the similar designation of the IBM 1130.		Trivia: The machine was set to be named "PDP-11/30" originally, but it was renamed to 11/20 because of the similar designation of the IBM 1130.
	</i>		</i>

			==See also==

			* [[KS11 Memory Protection and Relocation option]]

	==External links==		==External links==

Jnc: software, manuals, FMPS

2022-07-06T20:05:10Z

software, manuals, FMPS

← Older revision		Revision as of 20:05, 6 July 2022
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	[[Image:PDP11-20.jpg\|right\|150px\|thumb\|PDP11/20]]		[[Image:PDP11-20.jpg\|right\|150px\|thumb\|PDP11/20]]

	The PDP-11/20 was the first [[PDP-11]]; its [[KA11 CPU]] was built from a set of [[DEC card form factor\|quad width extended-length]] cards carrying SSI [[transistor-transistor logic\|TTL]] [[integrated circuit\|chips]], along with a few dual width cards. It introduced the [[UNIBUS]] as a universal path to connect together the [[Central Processing Unit\|CPU]], [[main memory]] and [[peripheral\|devices]].		The PDP-11/20 was the first [[PDP-11]] from [[Digital Equipment Corporation\|DEC]]; its [[KA11 CPU]] was built from a set of [[DEC card form factor\|quad width extended-length]] cards carrying SSI [[transistor-transistor logic\|TTL]] [[integrated circuit\|chips]], along with a few dual width cards. It introduced the [[UNIBUS]] as a universal path to connect together the [[Central Processing Unit\|CPU]], [[main memory]] and [[peripheral\|devices]].

	It was the only ~~one~~ to use discrete logic for its control circuits, as opposed to [[microcode]] (this was because the cheap, fast [[read-only memory\|ROMs]] needed for economical implementation of that approach did not exist yet at the time it was designed).		It was the only PDP-11 to use discrete logic for its control circuits, as opposed to [[microcode]] (this was because the cheap, fast [[read-only memory\|ROMs]] needed for economical implementation of that approach did not exist yet at the time it was designed).

	The CPU consisted of two and a half quad [[system unit]] [[backplane]]s (the two otherwise-unused slots were [[Small Peripheral Controller\|SPC]] slots, available for any [[peripheral]]) [[wire-wrap]]ped into a single unit (see [[KA11 CPU#Implementation\|here]] for details). They, and the [[KY11-A Programmer's Console\|KY11-A]] [[front panel]], were mounted in a [[BA11-C Mounting Box]].		The CPU consisted of two and a half quad [[system unit]] [[backplane]]s (the two otherwise-unused slots were [[Small Peripheral Controller\|SPC]] slots, available for any [[peripheral]]) [[wire-wrap]]ped into a single unit (see [[KA11 CPU#Implementation\|here]] for details). They, and the [[KY11-A Programmer's Console\|KY11-A]] [[front panel]], were mounted in a [[BA11-C Mounting Box]].
Line 19:		Line 19:
	One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.		One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.

	The KS11 was apparently DEC's first attempt at an add-on to ~~add~~ memory management to the -11/20. Other than a [https://www.bell-labs.com/usr/dmr/www/odd.html ~~fuuny~~ story], nothing is known of it.		The KS11 was apparently DEC's first attempt at an add-on to provide memory management to the -11/20. Other than a [https://www.bell-labs.com/usr/dmr/www/odd.html funny story], nothing is known of it. The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.
	The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.

	==Software==		==Software==

	An -11/20 was the first PDP-11 to run [[UNIX]], albeit a very early version.		The -11/20 was the machine that [[RSTS/E\|RSTS]] (called 'RSTS-11' when it was on the -11/20) ran on. Many other DEC PDP-11 [[operating system]]d (e.g. [[DOS-11]]) started out on the -11/20.

			It was the first PDP-11 to run [[UNIX]], albeit a very early version.

	== hampage.hu ==		== hampage.hu ==
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	==External links==		==External links==

			* [http://www.bitsavers.org/pdf/dec/pdp11/1120/ 11/20] - documentation at [[Bitsavers]]
			** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemManual.pdf PDP-11/20 system manual] (DEC-11-HR1B-D)
			** [http://www.bitsavers.org/pdf/dec/pdp11/1120/1120_SystemSchems_Feb70.pdf PDP-11/20 Engineering Drawings]
	* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook		* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook

Jnc: /* Extensions */ mention KS11

2022-07-06T19:47:20Z

Extensions: mention KS11

← Older revision		Revision as of 19:47, 6 July 2022
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	One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.		One was a [[co-processor]] for the multiply/divide functions, the [[KE11-A Extended Arithmetic Element]]; rather than additional [[instruction]]s in the CPU, it was implemented as a [[peripheral\|device]] on the [[bus]], making this model somewhat incompatible with the rest of the PDP-11's.

	The [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS, but also ~~tied~~ into the CPU; it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.		The KS11 was apparently DEC's first attempt at an add-on to add memory management to the -11/20. Other than a [https://www.bell-labs.com/usr/dmr/www/odd.html fuuny story], nothing is known of it.
			The extremely rare [[KT11-B Paging Option]] was logically an addition to the CPU, interposed between the KA11 and the UNIBUS (but also having a few ties into the CPU); it allowed [[hardware]]-based [[time-sharing]], and use of up to the full 248 KBytes of memory addressable by the UNIBUS.

	==Software==		==Software==

Jnc: /* External links */ +PDP-11/20 Processor Handbook

2022-04-05T23:16:04Z

External links: +PDP-11/20 Processor Handbook

← Older revision		Revision as of 23:16, 5 April 2022
Line 42:		Line 42:
	Trivia: The machine was set to be named "PDP-11/30" originally, but it was renamed to 11/20 because of the similar designation of the IBM 1130.		Trivia: The machine was set to be named "PDP-11/30" originally, but it was renamed to 11/20 because of the similar designation of the IBM 1130.
	</i>		</i>

			==External links==

			* [http://gordonbell.azurewebsites.net/Digital/PDP%2011%20Handbook%201969.pdf pdp11 handbook] - PDP-11/20 Processor Handbook

	{{PDP-11}}		{{PDP-11}}

	[[Category: UNIBUS PDP-11s]]		[[Category: UNIBUS PDP-11s]]

Jnc: bah, typo

2020-05-20T11:17:39Z

bah, typo

← Older revision		Revision as of 11:17, 20 May 2020
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	\| manufacturer = [[Digital Equipment Corporation]]		\| manufacturer = [[Digital Equipment Corporation]]
	\| introduced= 1970		\| introduced= 1970
	\| bus arch = [[UNIBUS]		\| bus arch = [[UNIBUS]]
	}}		}}
	[[Image:PDP11-20.jpg\|right\|150px\|thumb\|PDP11/20]]		[[Image:PDP11-20.jpg\|right\|150px\|thumb\|PDP11/20]]