10-12
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part III. The Hardware Interface
10.2.13 Partial Data Valid Indication (PSDVAL)
The 60x and local buses have an internal 64-bit data bus. According to the 60x bus
speciÞcation, TA is asserted when up to a double word of data is transferred. Because the
MPC8260 supports memories with port sizes smaller than 64 bits, there is a need for partial
data valid indication. The memory controller uses PSDVAL to indicate that data is latched
by the memory on write accesses or valid data is present on read accesses. The quantity of
the data depends on the memory port size and the transfer size. The memory controller
accumulates PSDVAL assertions, and when a double word (or the transfer size) is
transferred, the memory controller asserts TA to indicate that a 60x data beat was
transferred. Table 10-1 shows the number of PSDVAL assertions needed for one TA
assertion under various circumstances.
Figure 10-5 shows a double-word transfer on 32-bit port size memory.
Table 10-1. Number of PSDVAL Assertions Needed for TA Assertion
Port Size
Transfer Size
PSDVAL Assertions
TA Assertions
64
Any
1
1
32
Double word
2
1
32
Word/half word/byte (32-bit aligned)
1
1
16
Double Word
4
1
16
Word
2
1
16
Half/byte
1
1
8
Double word
8
1
8
Word
4
1
8
Half
2
1
8
Byte
1
1
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 266: ...8 34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 382: ...10 106 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 392: ...11 10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 430: ...Part IV viii MOTOROLA Part IV Communications Processor Module ...
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Page 980: ...A 4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Appendixes ...
Page 1002: ...Index 22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA INDEX ...
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