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SPARC CPU-5V Technical Reference Manual
OpenBoot
capabilities, as well as the VMEbus address and the size of the area being accessed. The data
capability is defined using the predefined constant cap-d32 which enables the VMEbus
master interface to access bytes (8bit data), half-words (16bit data), and words (32-bit data)
within the VMEbus area. The address capability is defined using the predefined constant capa32 that enables the VMEbus interface to access the extended address space (A32) of the
VMEbus.
The SBus slave interface is initialized by the second command which specifies that the
VMEbus is accessed when the SBus slot one (1) is being accessed at offsets A0.000016 to
BF.FFFF16 which corresponds to the VMEbus addresses in the range 4080.000016 to
409F.FFFF16 of the extended address space (A32).
ok
ok
ok
ok
ok
h# 4080.0000 cap-d32 cap-a32 1Meg 2 * 0 vme-master-range!
1Meg d# 10 * 1 1Meg 2 * 0 sbus-slave-range!
0 vme-master-ena
0 vme-master-map value vmebus
Finally, the third command enables any access to the VMEbus. The fourth command maps the
physical address area to be accessed in order to address the VMEbus to the virtual address
space of the processor and stores the virtual address in the variable vmebus. This variable may
be used to access the VMEbus area using the commands to read and write data provided by
OpenBoot.
ok vmebus 0 vme-master-unmap
ok
When the translation (SBus to VMEbus) defined by the contents of the register set associated
with the range number zero is no longer used, then the memory mapped to the processor’s
virtual address space to access the VMEbus must be released before the contents of this register
set are modified. This has to be done with the command vme-master-unmap as stated
above.
In the next example the VMEbus interface is initialized to allow accesses to the standard
address space (A24) of the VMEbus beginnig at address 98.000016 . The size of this area is
512KByte and the register set associated with the range number one (range# is 1) is used to
access this VMEbus area.
The first commands initializes the VMEbus master interface. It sets the data- and address
capabilities, as well as the VMEbus address and the size of the area being accessed. The data
capability is defined using the predefined constant cap-d16 which enables the VMEbus
master interface to access bytes (8bit data), and half-words (16bit data) within the VMEbus
area. The address capability is defined using the predefined constant cap-a24 that enables
the VMEbus interface to access the standard address space (A24) of the VMEbus.
The SBus slave interface is initialized by the second command which specifies that the
VMEbus is accessed when the SBus slot one (1) is being accessed at offsets 120.000016 to
127.FFFF16 which corresponds to the VMEbus addresses in the range 98.000016 to 9F.FFFF16
of the standard address space (A24).
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