Portage/ cultivation (process-centric)

Modification or rewriting of the source code to adapted it to stable hardware and software environment.

Pro: long term solution, software and hardware independence, adaptation of the source code to exact needs, access to support-community.
Cons: Cultivation is not suitable as a quick fix to ensure sustainability in short term, instead it requires effort and planning over many months and even years.

Check-list:
Acquire the code
Choose an open source license
Choose an open source operating system
Pay attention to the response speed of the software
Regularly check that the system is in working order
Regression tests
Check and validate results

Virtualization (date-centric approach)

Virtualization enables to run the software environment of a digital object on a current machine having the same architecture thanks to a virtual machine 

Pro: Virtualization maintains the original look, feel, and behavior of original source code. This strategy is easier to achieve than emulation.
Cons: This approach is sustainable only with compatible hardware environment.

Check-list:
Regularly check that the system is in working order
Migrate the hypervisor
Regression test
Check and validate results

Reinterpretation /work-in-progress

This strategy involves on the one hand rewriting of the source code to update the representation artifact and on the other hand, the replacement of the technological material by a current device which has the same social function.

Pro: In some circumstances, this process is part of the artwork.
Cons: lead to paramount modifications of the artwork aesthetic and delete any historic value.

Check-list :
Advise the artist(s)
Work directly with the artist(s)
Produce a good documentation of the process and explain the interpretative choices.

Storage/repair (techno-centric approach) 

This short term strategy is based on storage, care and when necessary the purchase of replacement devices.

Pro : maintain the original software and hardware environment.
Cons: short term solution, required availability of spare parts.

Check-list :
Purchase spares (see preventive conservation)
Regularly check that the system is in working order (see preventive conservation)
Maintain hardware
Replace or repair hardware elements as they fail

Migration (functionnality-centric)

Conversion of digital data to current format. Adapting a program so it runs on current operating systems, resulting a updating of material environment.

Pro:
This strategy maintains the software functionality without material pressure. No obsolescence pressure anymore (at least for a moment).
Cons:
Migration can lead to a loss of data difficult to predict and a modification of the artwork look and feel (visible equipment or software speed). It is a ongoing process with standard dependency.

Check-list:
Acquire the code
Choose an open source license
Pay attention to the response speed of software
Regularly check that the system is in working order
Subsequent migration
Regression test
Check and validate results

 

Emulation (date-centric approach) 

Emulation addresses the original hardware and software environment of a digital object, and recreates it on a current machine with a different architecture thanks to an emulator.

Pro: The emulation strategy is quite efficient in the sense that an emulator can be used to multiple other artworks. Emulators maintain the original look, feel, and behavior of original source code without the pressure of maintaining hardware.  
Cons: This is a temporary solution. With time, the emulator itself will become obsolete and unusable on contemporary computer systems. Required specialist skills and technological watch. This strategy is time-consuming and difficult to achieve.

Checklist:
Regularly check that the system is in working order
Regression tests
Check and validate results
Update the emulator (or maintain it if is developed in-house)