The Amiga 500 is considered one of Commodore's most important home computers, introduced in 1987; it was important because of how advanced the features were for the time. It was based on a Motorola 68000 CPU running at 7.16 MHz in NTSC versions and at 7.09 MHz for PAL ones, with the main version of 512 KB RAM expandable up to 9 MB. Its OCS provided respectable graphics performance, going up to 736×567 interlaced, with 32 colors out of 4096. The sound system consisted of four 8-bit PCM channels and could give out stereo at as high as 28 kHz. With the keyboard integrated and a compact design, it was ready for home users, while the multitasking operating system, AmigaOS, differentiated it from the rest. At a price the market could afford and featuring multimedia capabilities, this combination contributed to its popularity as it went on to sell about 2.6 million units worldwide.