MOTOROLA
Chapter 3. Device Programming
3-1
Chapter 3
Device Programming
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30
The programmable aspects of the MPC106 are primarily for use by initialization and error
handling software. This chapter describes the selectable address maps and the configuration
registers on the MPC106.
3.1 Address Maps
The MPC106 supports three address mapping configurations designated address map A,
address map B, and emulation mode map. Address map A conforms to the PowerPC
reference platform specification. Address map B conforms to the PowerPC microprocessor
common hardware reference platform (CHRP). The emulation mode map is provided to
support software emulation of x86 hardware.
The configuration signal DBG0, sampled during power-on reset, selects between address
map A and address map B. Map A is selected by using a pull-up resistor (DBG0 = 1); map
B is selected by using a pull-down resistor (DBG0 = 0). After reset, the address map can be
changed by programming PICR1[ADDRESS_MAP].
Emulation mode map can only be selected by software after reset by programming
ESCR1[EMULATION_MODE_EN].
3.1.1 Address Map A
Address map A complies with the PowerPC reference platform specification. The address
space of map A is divided into four areas—system memory, PCI I/O, PCI memory, and
system ROM space. Table 3-1, Table 3-2, and Table 3-3 show separate views of address
map A for the 60x processor, a PCI memory device, and a PCI I/O device, respectively.
When configured for map A, the MPC106 translates addresses across the 60x and PCI buses
as shown in Figure 3-1 through Figure 3-4.
Map A can be configured as contiguous or discontiguous by PICR1[XIO_MODE]. The
discontiguous map reserves a 4-Kbyte page for each 32-byte block addressed on the PCI
bus allowing each 32-byte block from 0 to 64KB – 1 in PCI I/O space to have distinct page
protection attributes. This can help when accessing PC-compatible I/O devices in the
ISA/PCI I/O space address 0 to 64KB – 1. The contiguous map as seen from the processor
is shown in Figure 3-1. The discontiguous map as seen from the processor is shown in
Figure 3-2.