1. xerox 560 computer system - The UK Mirror Service

Table 26. Functions of Memory Unit Configuration Control Panel Row (cont.)LabelSTARTING ADDRESSSwitch/Indicator7 switchesFunctionUsed to set the starting addresses of the memory units. From left toright the switches are labeled S12, S13, S14, S15, S16, S17, andS 18. Using the switches as a 7-position binary field, this allowsmemory to address up to 1 mi Ilion words.When the memory system comprises memory units of different sizes,some precautions are necessary to prevent false address recognitionas well as to prevent gaps in the memory range.1. If all memory units have sizes that are powers of two, they canall be different; they must, however, be assigned in order ofdecreasing size in the address continuum.For instance, three memory units can be used in this manner:Memory Unit No.Size--Address Range1 64K words o to 64K words2 32K words 64 to 96K words3 16K words 96 to 112K words2. If a memory unit has a size that is not a power of two, it mustbe situated in a memory system that satisfies the followingrules:a. All other memory units must have sizes that are a powerof two.b. The starting address of the non-power-of-two unit must bea multiple of the next power of two above the size of thatunit.c. The memory unit whose size is not a power of two must beat the upper end of the address range.Configuration Control Panel (CCP) 171