Joseph Robert Saddler, popularly known by his stage name Grandmaster Flash, is a Barbadian-American DJ, rapper and producer. He created a DJ technique called the Quick Mix Theory. This technique serviced the break-dancer and the rapper by elongating the drum breaks through the use of duplicate copies of vinyl. This technique gave birth to cutting and scratching. It also gave rappers better music with a seamless elongated bed of beats to speak on. He also invented the slipmat.