1. CSS Bu,
1.1 CSS Bu, Overview
The system bus is an N-port time-division multiplexed transmission switch. AIly of the N ports
(backplane positions/slots) can send (receive) transmissions to (from) any of the N ports,
including itself. Each transmission consists of a source port address, a destination port address, a
transmission type and 8 bytes of "data n. The transmission type determines what the ndata" field
contains. Error detection is provided for the source slot address, destination slot address and
transmission type fields and optionally provided for the "data" field. The design value of N is 14
(ports); the design clock rate is 20 MHz.
Modules installed in bus ports interact with each other by exchanging transmissions over the bus.
There are two types of transmissions, COMMANDS and RESPONSES. A module on the bus
begins an interaction with another module by sending a OOMMAND. The source of the
OOMMAND is the MASTER for that interaction; the destination of the OOMMAND|