AMBA is a well-established specification for processor bus architectures. It stands for Advanced Microcontroller Bus Architecture. The AMBA architecture standardizes the on-chip connection of different IPs and thus enables IP reusability.

AMBA specification defines three defferent buses: ASB, AHB and APB. AHB stands for Advanced High-performance Bus. This is the premiere bus used for high performance system modules such as memory controllers and Interrupt controllers. ASB stands for Advanced System Bus. This is an older version which has been superseded by AHB. Oki's ARM micros always use the AHB bus. APB stands for Advanced Peripheral Bus. It is a simple lower performance and low power bus used for low speed peripherals. Macrocells designed to interface with AMBA can be seen as building blocks which can be reused in future designs and mixed and matched in different combinations to realize complex systems in a shorter period of time.