Segments 1 and 2 of switch S5 define the state of the snoop control bus when an IP DMA controller is local bus master. As shown in Table 1-4, S5 segment 1 controls Snoop Control signal 1 on the MC680x0 processor. S5 segment 2 controls Snoop Control signal 0. Setting a segment to ON produces a logical 0; setting it to OFF produces a logical 1.
S5 varies in function according to the type of processor installed. For MVME162P4 boards with an MC68040 processor, setting segments 1 and 2 of switch S5 to OFF or leaving both segments set to ON (the factory configuration) inhibits snooping. Enabling snooping requires one of two possible ON/OFF combinations, according to the operation desired. MVME172P4 boards with an MC68060 processor have different snoop functionality.
The following table lists the snoop operations represented by the settings of S5 with both types of processor. For further details, refer to the MC68040 or MC68060 microprocessor user’s manuals listed in the Related Documentation appendix.
Note: Model Number: MVME162P-344SE, Characteristics: 32MHz 68040, 16MB SDRAM, 2 SIO, 4 DMA IP, SCSI/Ethernet is used on Universal UIC HSP4797L Hitachi Sanyo TCM-X100 P.C.B. Mount 6300901030