Editing PDP-11 (section)

=== Unibus models ===
[[File:Digital PDP11-IMG 1498 cropped.jpg|thumb|Original PDP–11/20 front panel]]
[[File:Pdp-11-70-panel.jpg|thumb|Original PDP–11/70 front panel]]
[[File:PDP-11-70-DDS570.jpg|thumb|Later PDP–11/70 with disks and tape]]

The following models use the [[Unibus]] as their principal bus:
* PDP–11/20 and PDP–11/15 – 1970.<ref name=pdp-11-faq-models>{{cite web |url=http://www.village.org/pdp11/faq.pages/11model.html |title=The PDP-11 FAQ |publisher=Village.org |date=2000-04-18 |access-date=2014-04-14 |url-status=dead |archive-url=https://web.archive.org/web/20160618161413/http://www.village.org/pdp11/faq.pages/11model.html |archive-date=2016-06-18 }}</ref> The 11/20 sold for $11,800.<ref>{{cite web |url=http://vintagecomputer.net/digital/PDP11-20/PDP11_Price-List_19691215.pdf |title=PDP-11 Price List (1969) |access-date=2020-10-19 |archive-date=2024-07-01 |archive-url=https://web.archive.org/web/20240701172332/http://vintagecomputer.net/digital/PDP11-20/PDP11_Price-List_19691215.pdf |url-status=live }}</ref> The original, non-microprogrammed processor was designed by Jim O'Loughlin. [[Floating point]] is supported by [[peripheral]] options using various data formats. The 11/20 lacks any kind of [[memory protection]] hardware unless retrofitted with a KS-11 [[Memory-mapped I/O|memory mapping]] add-on.<ref name="Ritchie">{{cite web |first=Dennis M. |last=Ritchie |author-link=Dennis Ritchie |title=Odd Comments and Strange Doings in Unix |url=https://www.bell-labs.com/usr/dmr/www/odd.html |publisher=[[Bell Labs]] |date=22 June 2002 |access-date=18 October 2015 |archive-date=3 January 2016 |archive-url=https://web.archive.org/web/20160103171003/http://www.bell-labs.com/usr/dmr/www/odd.html |url-status=live }}</ref> There was also a very stripped-down 11/20 at first called the 11/10,{{citation needed|date=August 2023}} but this number was later re-used for a different model.
* PDP–11/45 (1972),<ref name=pdp-11-faq-models/> PDP–11/50 (1973),<ref>{{Cite web |title=When was the PDP-11/50 released? |url=https://retrocomputing.stackexchange.com/a/28404/7208 |access-date=2024-02-05 |website=Retrocomputing Stack Exchange |language=en |archive-date=2024-07-01 |archive-url=https://web.archive.org/web/20240701172338/https://retrocomputing.stackexchange.com/questions/28397/when-was-the-pdp-11-50-released/28404#28404 |url-status=live }}</ref> and PDP–11/55 (1976)<ref name=pdp-11-faq-models/> – A much faster microprogrammed processor that can use up to 256&nbsp;[[kilobyte|KB]] of semiconductor memory instead of or in addition to [[Magnetic-core memory|core memory]] and support memory mapping and protection.{{r|Ritchie}} It was the first model to support an optional FP11 floating-point [[coprocessor]], which established the format used in later models.
* PDP–11/35 and PDP–11/40 – 1973.<ref name=pdp-11-faq-models/> [[Microprogram]]med successors to the PDP–11/20; the design team was led by Jim O'Loughlin.
* PDP–11/05 and PDP–11/10 – 1972.<ref name=pdp-11-faq-models/> A cost-reduced successor to the PDP–11/20. DEC Datasystem 350 models from 1975 include the PDP–11/10.<ref>{{cite journal |author=<!--Staff writer(s); no by-line.--> |date=July 30, 1975 |title=Time-Sharing Uses Emphasized for DEC Datasystem 350 Series |url=https://books.google.com/books?id=jT2fQqJplN8C&pg=PT29 |journal=Computerworld |volume=IX |issue=31 |pages=19 |access-date=November 4, 2022 |quote=All DEC Datasystem 350 models have PDP–11/10 CPUs |archive-date=March 6, 2023 |archive-url=https://web.archive.org/web/20230306042705/https://books.google.com/books?id=jT2fQqJplN8C&pg=PT29 |url-status=live }}</ref>
* PDP–11/70 – 1975.<ref name=pdp-11-faq-models/> The 11/45 architecture expanded to allow 4&nbsp;[[megabyte|MB]] of physical memory segregated onto a private memory bus, 2&nbsp;KB of cache memory, and much faster I/O devices connected via the Massbus.
* PDP–11/34 (1976<ref name=pdp-11-faq-models/>) and PDP–11/04 (1975<ref name=pdp-11-faq-models/>) – Cost-reduced follow-on products to the 11/35 and 11/05; the PDP–11/34 concept was created by Bob Armstrong. The 11/34 supports up to 256&nbsp;kB of Unibus memory. The PDP–11/34a (1978)<ref name=pdp-11-faq-models/> supports a fast floating-point option, and the 11/34c (same year) supported a [[cache memory]] option.
* PDP–11/60 – 1977.<ref name=pdp-11-faq-models/> A PDP–11 with user-writable microcontrol store; this was designed by another team led by Jim O'Loughlin.
* PDP–11/44 – 1979.<ref name=pdp-11-faq-models/> A replacement for the 11/45 and 11/70, introduced in 1980, that supports optional (though apparently always included) cache memory, optional FP-11 floating-point processor (one circuit board, using sixteen [[AMD]] [[Am2900|Am2901]] bit slice processors), and optional commercial instruction set (CIS, two boards). It includes a sophisticated serial console interface and support for 4&nbsp;MB of physical memory. The design team was managed by John Sofio. This was the last PDP–11 processor to be constructed using discrete [[logic gate]]s; later models were all microprocessor-based. It was also the last PDP–11 system architecture created by [[Digital Equipment Corporation]], later models were VLSI chip realizations of the existing system architectures.
* PDP–11/24 – 1979.<ref name=pdp-11-faq-models/> First VLSI PDP–11 for Unibus, using the "Fonz-11" (F11) chip set with a Unibus adapter.
* PDP–11/84 – 1985–1986.<ref name=pdp-11-faq-models/> Using the VLSI [[DEC J-11|"Jaws-11"]] (J11) chip set with a Unibus adapter.
* PDP–11/94 – 1990.<ref name=pdp-11-faq-models/> J11-based, faster than 11/84.