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Yale Library Emulation Viewer: Home

A guide to accessing emulated materials in the General Collections

About Emulation and EaaSI

Emulation refers to the process of recreating computer hardware with software. It allows users to run old operating systems and applications that would otherwise be incompatible with modern computers.

The EaaSI ("Emulation-as-a-Service Infrastructure") program, hosted at Yale University Library, is a Mellon and Sloan Foundation-funded project to make emulation technology more accessible to thousands of users at Yale and beyond. The Yale Library Emulation Viewer is one branch of the EaaSI program, using browser-based emulation to return many aging digital Library holdings to circulation. Instead of checking out a physical CD-ROM and tracking down the necessary, obsolete computer hardware to view it, Yale Library patrons can simply "check out" and view the contents of the disc from a link in the item's Library catalog record.

For more information on the full scope of EaaSI and its program of work, please see the program website.

Student Contributors

We recognize and thank the following Yale University students for their work in configuring the emulation environments to make this CD-ROM access possible. 

Current Student Staff

Claire Campbell (M.A. ’23)
Daraeno Ekong (’24)

Former Student Staff  

Justin Aubin (’21)
Andres Burgos (’22)
Nicole Cosme (PhD. ’26)
Esther Dominguez (’24)
Helen Dugmore ('22)
Paul Han (’20)
Yifan Li (M.C.S. '22)
Nina Lin (’24)
Leonardo Lizbinski (M.P.H. '20)
Aly Moosa (’25)
Alexa Murray (’19)
Vibhor Nayak (M.A.M., ’18)
Neeta Patel (M.A. ’24)
Jeff Pham (’24)
Mac Schmidt (’20)
Sasha Semina ('23)
Zoe Sinclair (’22)
Idris Sylvester (’20)
Nico Taylor (’22)
Eric Timperman (M.M., ’19)
Matt Tu (’22)
Kohei Yamaguchi (M.M.A., ’19)
Lucia You (M.A. ’22)
Kevin Zheng (M.P.H. '20)

How to Use the Yale Library Emulation Viewer

Please note that only one Yale library user can view an item in the emulation platform at a time. If a patron tries to open an item that is already open in another user's browser, the emulation platform will display an error message. Patrons must please wait and try again to view the item in emulation once the other user has ended their session (sessions are automatically ended after ten minutes). If your session times out, you will need to start a new emulation session.

YUL Emulation Viewer interface displaying "Thirstin's drinking water games & activities K-12"

Clicking on the emulation window will capture your mouse and keyboard input to the emulated computer - press "Esc" at any point during the session to free your mouse and keyboard to interact with your own computer again.

This menu appears at the top of the emulation window:

Restarts the entire emulation session - may be helpful for fixing or troubleshooting a crashed emulation.

Change Media
Some catalog items may contain multiple discs (e.g. an encyclopedia program with contents spread over 3 or 4 CD-ROMs). The user can click this button to switch which disc is loaded in the emulator, comparable to ejecting and loading different CD-ROMs into the drive on a physical computer.

The help button links back to this LibGuide for additional information and help.


Technical support for the Yale Library Emulation Viewer is available weekdays between the hours of 9-5 EST. The service may be used outside these hours, but support for troubleshooting technical issues will not be available until the next service window. Contact to submit a support request.

Please contact Access Services staff at for assistance using the service.


How do I find items that are available through the Yale Library Emulation Viewer?

Search for a CD-ROM title at Yale Library catalog at If the CD-ROM is available for viewing through the emulation service, a record for the emulation will be available with a link to the viewer in the catalog entry for the item.

To see all of the catalog entries for emulated CD-ROMs, search for "Yale Emulation-as-a-Service collection" at

A list of available CD-ROMs is provided in this guide.

Why can't I access a CD-ROM emulator?

Users must be authenticated via Yale University’s CAS Authentication Service to access a CD-ROM emulation. Access is limited to Yale students, faculty, staff, etc.

Concurrent user sessions for a single CD-ROM title are limited to the number of physical copies in the Library’s circulating collection, typically one. If you attempt to access a title already in use, try again later.

After I open an emulation session, how long may I access the session?

Sessions are automatically ended after ten minutes. If your session times out, return to the catalog entry for the item or the link in the libguide to open a new browsing session.

How can I share an emulation session with another user?

If you would like to share a link to an emulated CD-ROM with another Yale user, please share the link to the Yale library catalog record for the item. Please note: access is limited to authenticated Yale University users and only one user may access an item at a time.


Additional Resources

EaaSI Program website