Editing PDP-10 (section)

==Software==

===Operating systems===
The original PDP-10 [[operating system]] was simply called "Monitor", but was later renamed [[TOPS-10]].  Eventually the PDP-10 system itself was renamed the DECsystem-10. Early versions of Monitor and TOPS-10 formed the basis of Stanford's [[WAITS]] operating system and the [[CompuServe]] time-sharing system.

Over time, some PDP-10 operators began running operating systems assembled from major components developed outside DEC. For example, the main Scheduler might come from one university, the Disk Service from another, and so on. The commercial timesharing services such as [[CompuServe]], [[Embarq#History|On-Line Systems, Inc.]] (OLS), and [[Time-sharing#Rapidata as an example|Rapidata]] maintained sophisticated inhouse systems programming groups so that they could modify the operating system as needed for their own businesses without being dependent on DEC or others. There are also strong user communities such as [[DECUS]] through which users can share software that they have developed.

[[BBN Technologies|BBN]] developed their own alternative operating system, [[TENEX (operating system)|TENEX]], which fairly quickly became popular in the research community. DEC later ported TENEX to the KL10, enhanced it considerably, and named it [[TOPS-20]], forming the DECSYSTEM-20 line.

[[MIT]], which had developed CTSS, [[Compatible Time-Sharing System]] to run on their [[IBM 709]] (and later a modified [[IBM 7094]] system), also developed ITS, [[Incompatible Timesharing System]]<ref>{{cite web 
|title=A Brief History of Hackerdom: The Early Hackers
|quote=MIT ... built their own operating system, the fabled .. Incompatible Timesharing System
|url=http://catb.org/esr/writings/hacker-history/hacker-history-3.html}}</ref> to run on their [[PDP-6]] (and later a modified PDP-10);{{citation needed|date=August 2023}}

[[Tymshare]] developed [[Tymnet#Organization|TYMCOM-X]], derived from TOPS-10 but using a page-based file system like TOPS-20.<ref>{{Cite web |title=Tymshare Software |url=http://inwap.com/pdp10/tymshare/software/ |access-date=2023-09-24 |website=inwap.com}}</ref>

===Programming languages===
DEC maintained DECsystem-10 [[Fortran#FORTRAN IV|FORTRAN IV]] (F40) for the PDP-10 from 1967 to 1975<ref>{{cite web |last1=Digital Equipment Corp |title=DECsystem-10 FORTRAN IV (F40) Programmers Reference Manual |url=https://github.com/PDP-10/f40/blob/master/doc/DEC-10-LFLMA-B-D%20FORTRAN%20IV%20(F40)%20Programmer's%20Reference%20Manual.pdf |website=Github |publisher=Digital Equipment Corporation |access-date=15 April 2022}}</ref>

MACRO-10 (assembly language macro compiler), COBOL, BASIC and AID were supported under the multi processing and swapping monitors.<ref>{{Cite web |last=Equipment |first=Digital |date=1968 |title=PDP-10 Reference Handbook |url=https://bitsavers.org/pdf/dec/pdp10/1970_PDP-10_Ref/1970PDP10Ref_Part0.pdf |website=bitsavers.org }}</ref>

In practice a number of other programming environments were available including LISP and SNOBOL at the Hatfield Polytechnic site around 1970.