PDP-11 Bus

This document, ES:0002 dated April 2, 1969, provides a comprehensive technical description of the PDP-11 Uni-Bus architecture. It covers the thirty-signal bi-directional bus system, defining key signals like MSYN, SSYN, Control lines, and Data lines. The specification details various bus transactions, including Data-In (DATI), Data-Out (DATO), Data-Modify (DATM), Interrupts (INT), and console transfers. Furthermore, it explains the priority arrangement, describing how different devices (NPR, BR levels) request bus control and how the processor manages these requests through a priority hierarchy. Detailed step-by-step sequences for bus operations and the relative priority table are included to illustrate proper bus communication management.