MVME5100 Single Board Computer Programmer's Reference Guide

C
Introduction
The MVME2700 board, which uses a PReP memory map, is configured in
this example to occupy address space from 1000 0000 to 13FF FFFF
(64MB) on the VMEbus. The MVME5100, which defaults to a CHRP
memory map, occupies another 64MB address range, which in this
example is from 1400 0000 to 17FF FFFF. The PCI Slave Images
represent the view of the Universe on the PCI Local Bus. The VME Slave
Images represent the view of the Universe on the VMEbus. The purpose of
this application note is to demonstrate the process used to select the
appropriate Base and Bound values for the desired address mapping. In
this case, the entire 64MB of available memory space on the board has
been selected. The memory can be segmented by selecting different sizes
and mapping them using the remaining slave images within the Universe
device. In addition, by using the appropriate settings in the Control
register, the memory can be mapped as A24/D16, A16/D8, or other desired
addressing.
Once the Base and Bound values are determined, the correct value for the
Translate register must be selected so that the address presented to the bus
on the other side of the Universe is correct. Each of the Translate register’s
values were determined as follows:
2700 PCI Slave Translate
In the default memory map, PCI Memory space begins at C000 0000, the
first 1MB (100 0000) is set aside for other devices on the PCI Local Bus
that require PCI Memory. PowerPC addresses from C000 0000 to DFFF
FFFF are presented, zero based, on the PCI Local Bus. The Universe is
configured to accept PCI Memory addresses from 0100 0000 to 2000 0000
in PCI Slave Image 1. These addresses are passed unchanged to the
VMEbus. To translate a presented PCI address to a zero based VMEbus
address, the translation value of FF00 0000 was chosen. This value is the
required translation to make the presented address (0100 0000) become
0000 0000 on the VMEbus: 0100 0000 + FF00 0000 => 1 0000 0000.
2700 VME Slave Translate
For the VME Slave register, the Universe passes the presented address
unchanged onto the PCI Local Bus, unless translation is applied.
Consulting the memory maps available in the appropriate MVME
Programmer’s Guide, one finds that PowerPC memory is located at 8000
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