Probably I’m the last to find out, considering that a lot of time has passed since I checked the status of various emulators out there, but I just stumbled onto a very well made emulator for the Lisa. Development is a bit stuck at the moment, but the last version of the emulator, LisaEm 1.26 (2007.12.13) is quite stable and usable. It supports various platforms, and for Mac OS X (10.3.9 to 10.5.x) there’s a handy dmg file containing the documentation, the source code, and the pre-packaged application, so that it’s ready to run. Unlike other emulators, a ROM image is not required to start using the virtual Lisa, but of course you’ll need the Lisa Office System Software, otherwise everything will be pretty much unusable.
The emulator reads Disk Copy 4.2 image files, and you can find both system and application disks at The Mothership. Download the five .sit files containing the disk images for the 3.1 version of the Office System Software, and follow the instructions in the LisaEm documentation to install the software in the virtual machine.
What’s wonderful is the visual impact of this emulator — everything is faithfully emulated: the software and the hardware (even acoustically, you hear the actual sounds of a functioning Lisa). Here’s a screenshot after installing the Office System Software (click to enlarge):
That’s right: an image of a true Lisa in front of you. If you insert a virtual floppy, you’ll see a real floppy inside the drive. If you turn the Lisa off, the power light (in the lower right corner) will turn off too. All feels very real and enjoyable.