The 3B20D Processor & DMERT operating system: 3B20D file memory systems

The 3B20D file memory system employs microprocessor-based intelligent Disk File Controllers (DFC), each supporting a complement of one to eight 300-megabyte disk drives. The DFC communicates with the system via a high-capacity dual-serial channel link to the Direct Memory Access Controller (DMAC) that accesses the processor's main memory. The DFC communicates with its disk files via an industry standard interface. The disk power system is also microprocessor based. The system operates disk drives on commercial ac power until a power failure occurs. The disks are then switched under microprocessor control to inverter power until the commercial ac fault is cleared, at which time the disk is returned to commercial ac power.