2.4. MIOC Architecture

The problem of memory contention was solved when HP introduced the first data-flow manager, a tri-bus arbitrator that acted as a memory and I/O controller (MIOC). This architecture is illustrated in Figure 2-4.

Figure 2-4. MIOC architecture.

The data-flow manager provided three main functions: (1) bus arbitration; (2) timing; and (3) buffering between the processor, memory, and I/O.

In this architecture, the width of the memory bus was increased to 128 bits to allow multiple concurrent I/O transactions.