---
keywords: [DECSys-7, "PDP-7", 1960s, 1965]
image: ./decsys.webp
description: "! DECSys-7 was an operating system for the DEC PDP-7 computer. It was DEC's first operating system for a computer smaller than its 36-bit timesharing systems."
sidebar_position: 1
---

import DocCardList from '@theme/DocCardList';

# ! DECSys-7

![! DECSys-7](./decsys.webp)

! DECSys-7 was an operating system for the DEC PDP-7 computer. It was DEC's first operating system for a computer smaller than its 36-bit timesharing systems. We can run it on the SIMH PDP-7 emulator.

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## Manuals

You can download the ! DECSys-7 manual from here:

- [! DECSys-7 Operating Manual (7-5-S)](http://bitsavers.org/pdf/dec/pdp7/DECSYS-7_OperMan.pdf)

You may also be interested in the PDP-7 and PDP-4 manuals. They were the computers on which ! DECSys-7 was supposed to run. You can download them from Bitsavers:

- [PDP-7 Manuals](http://bitsavers.org/pdf/dec/pdp7/)
- [PDP-4 Manuals](http://bitsavers.org/pdf/dec/pdp4/)

Out of those, these are the ones referenced by the Operating Manual:

- [PDP-7 User's Handbook (F-75)](http://bitsavers.org/pdf/dec/pdp7/F-75_PDP-7userHbk_Jun65.pdf)
- [PDP-7 Programming Manual, FORTRAN II (7-2-S)](http://bitsavers.org/pdf/dec/pdp7/PDP-7_FortranII.pdf)
- [PDP-7 Programming Manual, Symbolic Assembler (7-3-S)](http://bitsavers.org/pdf/dec/pdp7/PDP-7_AsmMan.pdf)
- [PDP-7 Programming Manual, Debugging System (7-4-S)](http://bitsavers.org/pdf/dec/pdp7/PDP-7_DDT_Ref.pdf)
- [PDP-7 DECTOG Program, PDP-7 Program Library (7-20-10-FB)](http://bitsavers.org/pdf/dec/pdp7/DIGITAL-7-20-IO-FB_DECTOG.pdf)

## Related Pages

- [VirtualHub Screenshots](https://screenshots.virtualhub.eu.org/1960s/1965/decsys/)
- [Wikipedia](https://en.wikipedia.org/wiki/PDP-7#Software)
- [Computer History Wiki PDP-7 page](https://gunkies.org/wiki/PDP-7)
- [Computer History Wiki PDP-4 page](https://gunkies.org/wiki/PDP-4)

## Credits

- The manuals were taken from [Bitsavers](http://bitsavers.org).