Citrix Multiuser 1.0

Citrix Multiuser is a customized version of Microsoft OS/2 1.21 that turns it in to a real multi-user operating system. With Citrix Multiuser, users can connect and simultaneously run character cell based applications from remote serial terminals. To prevent users from interfering with each other, it adds security permissions to devices and files. It can use multi-port serial port boards like the Digiboard, or any serial device that has OS/2 1.21 drivers.

Citrix Multiuser OS/2 does not support running Presentation Manager based application or DOS executables, and programs can not use graphics modes. It also does not have support for networking.

This product was released just days before the IBM-Microsoft separation, which was an almost instant fatal blow as Citrix was licensing OS/2 code through Microsoft.

As a result, Citrix Systems had to backtrack and instead focused on making MS-DOS multi-user until eventually they released a Windows NT based version.

The client software application used on PCs to communicate with a server is Citrix Multiuser Link.

Wanted: the DOS based Citrix system.


Installation instructions

To install on a faster computer, you must first apply the OS/2 speed patches described here to the boot disk:

To summarize, replace all occurrences of: B8 F4 01 BB C8 00 F7 E3 F7 F1 with B8 F4 01 BB C8 00 F7 E3 90 90

It currently will not install in PCem (or some real hardware apparently) due to a known bug with OS/2's FDISK. Unlike normal OS/2, Citrix Multiuser's setup will not let you skip that.

The CSD update disks must be installed from maintenance mode. To do that, use the Citrix Multiuser OS/2 boot disk, and after install starts from the second disk, hit escape.

A little more information can be found in this Software Spotlight.

Product type
Citrix Systems Inc
Release date
Minimum CPU
386SX, 386, or 486
Minimum RAM
Minimum free disk space
User interface
Download count
2 (2 for release)


Download name Version Language Architecture File size Downloads
Citrix Multiuser 1.0 (5.25-1.2mb) 1.0 English 5.55MB 2
Citrix Multiuser 1.0 Manuals 1.0 English 181.27MB 0


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