This is running a program on a future computer which makes it emulate the hardware of an older computer, enabling software written for that computer to run, and therefore nothing ever needs to be migrated. Writing such software is not trivial (although in theory it only needs to be done once). AA: I think this is the Macintosh Lisa project?? You can also emulate specific applications (AA: I’m thinking of Marathon here), but this involves a huge amount of retro-engineering, if the format is proprietary. Stricly speaking, you are not actually running the original program at all, just something pretending to be the program (I’m not running Marathon, I’m running Aleph One).

Presumably the DOS command window in today’s Windows systems is an OS emulator. (Rich says it is.) And you can run the original 1981 VisiCalc spreadsheet software on it – as far as I’m aware the code used is still the original code, not a rewritten code (http://www.bricklin.com/history/vcexecutable.htm accessed 28.11.2007).

Emulation is attractive, as in theory it captures all aspects of the original file – the content, the formulae, their relationships, the behaviour, the apperance. But it is very difficult, not least because it all has to be worked out while the original platform is still active. You then need to preserve the emulator, the OS, the application installation files and the records. (So you need to remember to keep them.) It’s probably too much work for individual files like spreadsheets. It’s worth noting that emulators have only really been done for games, not for spreadsheet programs.

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