4-13
Themis Computer
4—Universe II Description
Slave Image Programming
4.3.2.2 VMEbus Fields
The VMEbus fields cause the Universe II to generate the appropriate VMEbus
address, AM code, and cycle type, allowing PCI transactions to be mapped to a
VMEbus transaction. It is possible to use invalid combinations, such as block trans-
fers in A16 space. This may cause illegal transactions on the VMEbus. All accesses
beyond the 4-GB limit will wrap around to the low address range.
.
Figure 4-3.
Address Translation for PCI Bus to VMEbus Transfers
Table 4-8.
PCI Bus Fields for PCI Bus Target Image
Field
Register Bits
Description
base
BS[31:12] or BS[31:16] in LSIx_BS
Multiples of 4 or 64 KBytes
(base to bound: maximum of 4
GB)
bound
BD[31:12] or BD[31:16] in LSIx_BD
address space
LAS in LSIx_CTL
Memory or I/O
Warning:
The address space of a PCI bus slave image must not overlap with the
address space for the Universe II’s control and status registers.
A32 Image
Offset [31..12]
PCI [31..12]
PCI [11..0]
+
VME [11..0]
VME [31..12]
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