Lisa Version 2.90 [exclusive] -

Create a full snapshot of your current system data store.

Lisa Version 2.90 is the culmination of everything learned in the Version 2 lifecycle. It strips away the experimental features that didn't quite work, refines the ones that did, and packages them in a build that is stable, fast, and predictable. For enterprise clients and stability-focused developers, this makes Version 2.90 an incredibly attractive option. Lisa Version 2.90

The engineers behind Lisa Version 2.90 taught us that obsolescence is a choice. You can always build a bridge. Create a full snapshot of your current system data store

Net Protocol Suite™ 2.90 – Release Notes - Teledyne LeCroy Net Protocol Suite™ 2

By late 1984, the Macintosh was winning the public's heart. Lisa 2.90 borrowed heavily from its younger sibling. The file manager received a cleaner, icon-based navigation system, including the ability to drag icons directly to the trash. The confusing "Stationery Pad" feature was replaced with a simpler "Duplicate" command.

Why does 2.90 matter? Because it was the last pure-Lisa OS. Immediately after 2.90's release, Apple launched the program, allowing Lisa owners to emulate the Macintosh. By mid-1985, Apple rebranded the Lisa 2/10 as the Macintosh XL and killed the Lisa Office System entirely.