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SECTION 4

PROGRAMMING

REGISTER ACCESS

The SMIP II modules are VXIbus register-based devices for high-speed data transfers. Register- based programming is a series of reads and writes directly to the switch module registers. This eliminates the time for command parsing thus increasing speed.

ADDRESSING

The VTI switching modules utilize either the A24 or A32 space of the shared-memory architecture. To read or write to a module register, a register address needs to be specified. This is done by using the offset value (assigned by the resource manager) and multiplying it by 256 or 64 k to get the base address in A24 or A32 address space, respectively

A24 Base Address = Offset value * 0x0100 (or 256)

A32 Base Address = Offset value * 0x10000 (or 65,536)

The A24 or A32 offset value, assigned by the resource manager, can also be accessed by reading the A16 Offset Register. To address the A16 Offset Register use the following formula:

A16 Base Address = (Logical Address * 64) + 0xC000 (or 49,152)

then

A16 Offset Register Address = A16 Base Address + 6

See Table 4-1for A16 Memory Map and A24/A32 address space allocation.

SM7100 Programming

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VXI SM7100, Microwave Matrix user manual Register Access, Addressing