Happy Mac

A Happy Mac is the normal boot up icon displayed by Macintosh models running older versions of Mac OS or Mac OS X from Apple Computer. It was replaced by a large grey Apple logo with the introduction of Mac OS X 10.2.

Process
When a Macintosh computer is booted, it makes a startup beep or chime as the ROM is loaded. No sound will indicate an electrical or mechanical problem.

After the ROM is loaded and diagnostics are completed, the screen will turn gray as the computer looks for a bootable operating system. If the diagnostics fail, a Sad Mac icon will appear instead, indicating a problem in the boot sequence.

If the computer cannot immediately locate a bootable system file (whether from an internal hard drive or floppy disk), a blinking floppy (or folder) icon with a question mark will be displayed until such a disk is inserted or mounted.

Once a bootable system file is found, a Happy Mac icon will appear, followed by the welcome or startup screen of the version of Mac OS that is being loaded. In classic Mac OS, icons of loaded extensions and control panels may be displayed at the bottom. After the system has completed loading, the Finder will normally be launched by default and the desktop will appear.

Icon types
On Old World ROM Macs, the Happy Mac image is a monochrome icon stored in the Macintosh Toolbox ROM. A monochrome floppy icon with question mark is stored in there for when the system file cannot be found.

On New World ROM Macs, the Happy Mac image is a color icon stored in the Mac OS ROM file on the boot drive. A color folder icon with question mark is stored in there for when the system file cannot be found.

Articles

 * Changing Your Startup Drive by Dan Knight at Low End Mac (1998-03, updated 2001-12)
 * Remember starting up to a Happy Mac? by Christopher Phin at Macworld (2015-11-24)