What operating system did McDonald's introduce when it reopened as a hamburger restaurant in 1948?

When McDonald's reopened as a hamburger restaurant in 1948, it introduced the Speedee Service System.

Richard and Maurice McDonald redesigned their San Bernardino operation after deciding that barbecue dishes and carhop service were too slow and labor-intensive. They simplified the menu, moved to counter service, used disposable packaging, and concentrated on hamburgers, fries, milkshakes, and soft drinks.

The system emphasized repeatable preparation and rapid service. Its name came from Speedee, a chef character used in the company's early branding. The approach helped turn restaurant work into a standardized production process and later influenced the wider fast-food industry.

The Speedee Service System should not be confused with Speedee himself. Speedee was the mascot; the Speedee Service System was the operating method built around speed, limited choice, and consistency.