Duplex CPU & Dual Expansion backplane, 8 I/O slots, use CS1D-PA207R power supplies only

Duplex expansion backplane, 9 I/O slots, use CS1D-PA207R power supplies only

Duplex CPU, 30K steps program / 64K words data memory

CPU for duplex system, 60K steps program, 128K words data memory, 7 duplex expansion racks max, hot standby CPUs, hot swap I/O

CPU for duplex system, 250K steps program, 448K words data memory, 7 duplex expansion racks max, hot standby CPUs, hot swap I/O

Duplex CPU, 250K steps program / 448K words data memory