---
layout: page
title: "IBM PC XT (Model 5160, 640Kb, 10Mb Drive) with Color Display running Multitasking MS-DOS 4.00"
permalink: /devices/pc/machine/5160/cga/640kb/dos400m/
redirect_from:
  - /configs/pc/machines/5160/cga/640kb/dos400m/
  - /videos/pcjs/
machines:
  - type: pc-dbg
    id: ibm5160
---

Multitasking MS-DOS 4.00
---

This simulation demonstrates the first unearthed copy of Microsoft's "multitasking" version of MS-DOS.
The [original images](/disks/pc/dos/microsoft/4.0M/) were discovered by the [PCjs Project](/docs/about/) in March 2013.
This version of MS-DOS was never officially released in North America.  More information is available at
[Wikipedia](http://en.wikipedia.org/wiki/Multi-tasking_MS-DOS_4.0) and [OS/2 Museum](http://www.os2museum.com/wp/?p=1769).

Note: The designation "4.0M" is not an official version number; it's an internal version number used only to
differentiate these disk images from those of the official MS-DOS 4.00 release in July 1988. 

The PCjs machine configuration below boots MS-DOS 4.0M.  To access the MS-DOS "Session Manager" after it's booted,
tap the **Alt** key.

{% include machine.html id="ibm5160" %}