Motorola MPC8260 - Manual (Page 236)

8-4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part III. The Hardware Interface
Figure 8-2. 60x-Compatible Bus Mode
8.3 60x Bus Protocol Overview
Typically, 60x bus accesses consist of address and data tenures, which in turn each consist
of three phasesÑarbitration, transfer, and termination, as shown in Figure 8-3 The
independence of the tenures is indicated by showing the data tenure overlap the next
address tenure), which allows split-bus transactions to be implemented at the system level
in multiprocessor systems. Figure 8-3 shows a data transfer that consists of a single-beat
transfer of as many as 256 bits. Four-beat burst transfers of 32-byte cache blocks require
data transfer termination signals for each beat of data. Note that the MPC8260 supports port
sizes of 8, 16, 32, and 64 bits and requires the additional bus signal, PSDVAL, which is not
BR
BG
TS
A[0Ð31]
TT[0Ð4]
TSIZ[0Ð3]
TBST
CI
WT
GBL
AACK
ARTRY
DBG
D[0Ð63]
DP[0Ð7]
TA
TEA
MPC8260
I/O
MEM
Data + Attributes
Address + Attributes
Memory Controller Signals
External Device
BR
BG
DBG
Latch
Latch &
DRAM MUX
Memory Control Signals
AP[0Ð3]
TS
APE