Rewriting the Window Manager in Assembly
The window manager was a cornerstone of the Macintosh user interface, leveraging QuickDraw's "region clipping" to handle dynamic window operations. Originally written in Pascal for the Lisa by Bill Atkinson, it was my task to rewrite it in 68000 assembly and tailor it for the Mac. The first step: porting Atkinson's logic, tested via a small program called "Window Manager Demo."
Animating Windows with QuickDraw
To stress-test clipping, I repurposed a fast 16x16 pixel animation routine I’d written earlier—bouncing balls that showcased the Mac’s graphics speed. In the demo, dozens of animated balls per window ensured full coverage, revealing any clipping flaws.
Susan Kare’s Creative Touch
When Susan Kare joined in January 1983, I enlisted her to replace the generic balls with 16x16 bitmaps. Soon, windows teemed with bouncing Macs, apples, and even alligators—transforming the demo into a playful showcase.
Steve Jobs’ Pepsi Challenge
Months later, Steve Jobs requested a special demo for John Sculley, Pepsi’s president: "Impress him, and Pepsi might buy thousands of Macs." Susan designed Pepsi-themed sprites—cans and caps—which I added to the demo.
The Demo’s Unexpected Twist
During Sculley’s visit, he reacted warmly to the Pepsi elements but remained detached otherwise. Weeks later, we learned the truth: Sculley was interviewing for Apple’s CEO role, swayed by Steve’s pitch—"Change the world or sell sugar water?" The demo, it turned out, was a quiet audition.
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