CHAPTER TWO
2-2
bc635VME/bc350VXI Time and Frequency Processor (Rev. E)
Symmetricom Inc
2.1 VMEbus BASE ADDRESS SELECTION
Base address selection for the VMEbus requires the setting of switch SW1 (A6 through A13) and
SW2 (A14 and A15). The bc635VME occupies 64 bytes in the A16 address space and can be
freely located on any 64 byte boundary. The correspondence of the switch positions to the
address bits is illustrated in Table 2-1.
Table 2-1
Address Bits Switch Positions
SW2
SW1
Address Bit
A15 A14 A13 A12 A11 A10 A09 A08 A07 A06
Switch Number
2
1
8
7
6
5
4
3
2
1
A16 address range used.
(The BASE address is
on the left side.)
Example switch
settings for SW1
and SW2.
0
0
0
0
0
0
0
0
0
0
0x0000 - 0x003F
1 = OPEN or
OFF
0
0
0
0
0
0
0
0
0
1
0x0040 - 0x007F
0 = CLOSED or
ON
0
0
0
0
0
0
0
0
1
0
0x0080 - 0x00BF
0
0
0
0
0
0
0
0
1
1
0x00C0 - 0x00FF
0
0
0
0
0
0
0
1
0
0
0x0100 - 0x013F
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
…
1
1
1
1
1
1
1
0
1
1
0xEFC0 - 0xFEFF
1
1
1
1
1
1
1
1
0
0
0xFF00 - 0xFF3F
1
1
1
1
1
1
1
1
0
1
0xFF40 - 0xFF74
To select a base address, set each of the switches to the logical zero (CLOSED
or
ON) or the
logical one (OPEN or OFF) state.
2.2 bc350VXI LOGICAL ADDRESS SELECTION
Logical address selection for the VXIbus requires the setting of switch SW1 (A6 through A13).
The bc350VXI occupies 64 bytes in the A16 address space and can be located at any of the 256
logical addresses within the VXIbus. The correspondence between the switch positions and the
address bits, and the logical state corresponding to a switch setting follows the description
provided in Section 2.1
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