Windows 98 (codenamed Memphis while in development) is a graphical operating system by Microsoft. It is the second major release in the Windows 9x line of operating systems and the successor to Windows 95. It was released to manufacturing on May 15, 1998 and to retail on June 25, 1998.

Like its predecessor, Windows 98 is a hybrid 16-bit and 32-bit monolithic product with the boot stage based on MS-DOS. Windows 98 was succeeded by Windows 98 Second Edition (SE) on May 5, 1999, which in turn was succeeded by Windows ME on September 14, 2000. Microsoft ended mainstream support for Windows 98 and 98 SE on June 30, 2002, and extended support on July 11, 2006.

The startup sound for Windows 98 was composed by Microsoft sound engineer Ken Kato, who considered it to be a "tough act to follow".

System requirements

System requirements include:

Intel 80486DX2 66 MHz or a compatible CPU with a math coprocessor[39] (Pentium processor recommended)
16 MB of RAM (24 MB recommended; it is possible to run on 8 MB machines with /nm option used during the installation process)
At least 500 MB of disk space. The amount of space required depends on the installation method and the components selected, but virtual memory and system utilities as well as drivers should be taken into consideration.
Upgrading from Windows 95 (FAT16) or 3.1 (FAT): 140–400 MB (typically 205 MB).
New installation (FAT32): 140–255 MB (typically 175 MB).
VGA or higher resolution monitor (640×480)
CD-ROM or DVD-ROM drive (floppy install is possible but slow)
Microsoft Mouse or compatible pointing device (optional).
Users can bypass hardware requirement checks with the undocumented /NM setup switch. This allows installation on computers with processors as old as the 80386.

Windows 98 is not designed to handle more than 1.0 GB of RAM without changes. Workarounds and third-party patches are available to fix this shortcoming.

Both Windows 98 and Windows 98 Second Edition have problems running on hard drives bigger than 32 GB and certain Phoenix BIOS settings. A software update fixed this shortcoming. In addition until Windows XP with Service Pack 1, Windows was unable to handle hard drives that are over 137 GB in size with the default drivers, because of missing 48-bit Logical Block Addressing support. While Microsoft never officially fixed this issue, unofficial patches are available to fix this shortcoming in Windows 9x, although the author stated that data corruption is possible and did not guarantee that it would work as expected.