The RSP1 is the main system processor module for the Cisco 7505. It combines all of the switched routing and high-speed switching functions of the separate Route Processor (RP) and Switch Processor (SP), which are used in the Cisco 7000 series routers. Because the RSP1 combines the RP and SP functions, four slots are available for interface processors, allowing greater port density. The RSP1 contains the central processing unit (CPU) and most of the memory components for the Cisco 7505.The Cisco Internetwork Operating System (Cisco IOS) software images reside in Flash memory, which is located either on the RSP1, in the form of a single in-line memory module (SIMM), or on up to two Personal Computer Memory Card International Association (PCMCIA) cards (called Flash memory cards) that insert in the two PCMCIA slots on the front of the RSP1. Storing the Cisco IOS images in Flash memory enables you to download and boot from upgraded Cisco IOS images remotely or from software images resident in the RSP1 Flash memory, without having to remove and replace read-only memory (ROM) devices. The high-speed switching section of the RSP1 communicates with and controls the interface processors on the high-speed CyBus. This section decides the destination of a packet and switches it based on that decision. The RSP1 uses a 16-million-instructions-per-second (mips) processor to provide high-speed, autonomous switching and routing.