While additions had been relatively limited, so had fixes to some of the underlying oddities of the system architecture. Running MultiFinder normally required larger amount of RAM and a hard drive, but these were becoming common by the late 1980s. Most notable among these was the single-tasking model, the replacement of which had first been examined in 1986's 'Switcher' and then replaced outright with MultiFinder in System 5.

However, many of the assumptions of this model were no longer appropriate. That is, the machine was geared towards a single user and task running on a floppy disk based machine of extremely limited RAM. These limited changes meant that the original Mac system remained largely as it was when initially introduced. This initially shipped in three volumes, adding another to describe the changes introduced with the Mac Plus, and another for the Mac II and Mac SE. Some perspective on the scope of the changes can be seen by examining the official system documentation, Inside Macintosh. Major additions were fairly limited, notably adding Color QuickDraw and MultiFinder in System 6. The development of the Macintosh 'Systems' up to System 6 followed a fairly smooth progression with the addition of new features and relatively small changes and upgrades over time. System 7 was developed for Macs that used the Motorola 680x0 line of processors, but was ported to the PowerPC after Apple adopted the new processor. With the release of version 7.6 in 1997, Apple officially renamed the operating system 'Mac OS', a name which had first appeared on System 7.5.1's boot screen. 'System 7' is often used generically to refer to all 7.x versions.

Features added with the System 7 release included virtual memory, personal file sharing, QuickTime, QuickDraw 3D, and an improved user interface. It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997. It was introduced on May 13, 1991, by Apple Computer. System 7 (codenamed 'Big Bang' and sometimes erroneously called Mac OS 7) is a single-user graphical user interface-based operating system for Macintosh computers and was part of the classic Mac OS line of operating systems. Monolithic for 68k, nanokernel for PowerPC

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