Dates are approximate. I’d argue 1996 and 2006 were smaller epochs mostly localized to the PC industry; but 2001 and 2011 had much larger rippling effects.
The Apple II and Commodore PET become popular in business with titles such as VisiCalc, the early computer spreadsheet. This proves the utility of PCs in that field. The Apple II also finds a niche in education with titles like the Oregon Trail.
The Commodore 64 and ZX Spectrum become very popular computers due to their decent set of features for a very low price. The IBM PC comes out and legitimizes the personal computing industry. Poor quality titles and overproduction cause the Atari 2600 and its competitors to collapse, creating a stigma around video game consoles.
The Macintosh had introduced a bitmapped, easy to use system with a consistent HIG, and others followed. The Acorn Archimedes comes out in the UK, and its CPU, the ARM2, becomes the basis of CPUs in many smartphones and tablets today. The Amiga 500 and Atari S, with their affordable price tags, put affordable, yet fast and richly graphical computers in the hands of the masses. The IBM PS/2 comes out, with VGA graphics, and the fading of IBM’s power in the PC industry. Windows 2.0 comes out and starts to become popular, initially as a runtime for applications.
The Multimedia PC specification, along with the decline of Commodore had ensured PCs would become the dominant platform in not just multimedia, but in computing. CD-ROMs become popular, making software distribution easier and the rise of more complex games, even with full motion video. Windows 3.1 ensured Windows’ dominance in the coming years with its popularity and ease of development. The 486DX2-66 was a major yet widespread performance improvement, which continued to stay relevant in spite of new Pentium processors.
Windows 95 had come out to much fanfare. It displayed clear technical superiority to Windows 3.1, as well as a massively improved user experience. Despite this, DOS gaming held together for longer, to be ended with the increasing complexity of features and hardware, which Windows handled with ease with DirectX and Plug and Play. The web was becoming popular, and the browser war between Microsoft’s Internet Explorer and Netscape was heating up, leading to an antitrust lawsuit against Microsoft. The Pentium Pro offered workstation speed with Intel compatibility, signalling the beginning of the end for RISC CPUs in workstations.
The Gigahertz war had rapidly disrupted the performance of PCs. Within a year, CPUs had jumped from 500 MHz “Katmai” Pentium 3s to 1 GHz “Coppermine” Pentium 3 and “Thunderbird” Athlons. Windows XP and Mac OS X had moved the consumer PC industry to fully 32-bit modern operating systems, and took full advantage of this rapid gain in performance. 3dfx had entered bankruptcy, and the free-for-all of the 90s that had shifted to 3dfx dominance with its Glide API had overnight shifted to the current duopoly of NVidia and ATI. Broadband internet, both DSL and Cable, had become increasingly popular, shifting consumers from slow lines they must manually connect to, instead to much faster lines that are always connected and don’t disrupt the phone line.
While Windows Vista’s vision of the future (the digital hub) was interrupted by the iPhone, it forced many major changes in the PC industry. The minimum specifications had increased; disrupting the plateau created by XP's stagnation, and did invasive changes needed to improve system security. Intel’s new Core 2 CPUs would bring power-efficient SMP and 64-bit to the masses, as well as hurt AMD’s competitiveness. The OLPC and Eee PC would signal the importance of the low end. The combination of netbooks and the major performance improvements brought by Core 2 begin the plateau we know today. The internet was starting to become more popular and capable. Streaming video like Netflix and YouTube become popular in this time, and later start to push traditional video out of market.
The smartphone becomes the new default computing platform. The iPhone 4 on Verizon and Android phones becoming cheap enough to become free with cellular contracts would disrupt the industry. The iPad comes out and prompts more rethinking about computing. Both types of devices carry on the importance of cheap and low end hardware that the netbooks had shown before. The Internet becomes increasingly essential in not just computing, but people’s lives.