Motorola MPC8260 User Manual
MOTOROLA
Chapter 8. The 60x Bus
8-19
Part III. The Hardware Interface
8.4.3.7 60x-Compatible Bus ModeÑSize Calculation
To comply with the requirements listed in Table 8-8 and Table 8-9, the transfer size and a
new address must be calculated at the termination of each beat of a port-size transaction. In
single-MPC8260 bus mode, these calculations are internal and do not constrain the system.
In 60x-compatible bus mode, the external slave or master must determine the new address
and size. Table 8-10 describes the address and size calculation state machine. Note that the
address and size states are for internal use and are not transferred on the address or TSIZ
pins. Extended transactions (16- and 24-byte) are not described here but can be determined
by extending this table for 9-, 10-, 16-, 23-, and 24-byte transactions.
new address must be calculated at the termination of each beat of a port-size transaction. In
single-MPC8260 bus mode, these calculations are internal and do not constrain the system.
In 60x-compatible bus mode, the external slave or master must determine the new address
and size. Table 8-10 describes the address and size calculation state machine. Note that the
address and size states are for internal use and are not transferred on the address or TSIZ
pins. Extended transactions (16- and 24-byte) are not described here but can be determined
by extending this table for 9-, 10-, 16-, 23-, and 24-byte transactions.
Table 8-9. Data Bus Contents for Write Cycles
Transfer
Size
TSIZ[0Ð3]
Address
State
1
A[29Ð31]
1
Address state is the calculated address for port size
External Data Bus Pattern
0Ð7
8Ð15
16Ð23
24Ð31
32Ð39
40Ð47
48Ð55
56Ð63
Byte
(0001)
000
OP0
2
2
OPn: These lanes are read or written during that bus transaction. OP0 is the most-signiÞcant byte of a word
operand and OP7 is the least-signiÞcant byte.
Ñ
3
3
Ñ Denotes a byte not driven during that write cycle.
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
001
OP1
OP1
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
010
OP2
Ñ
OP2
Ñ
Ñ
Ñ
Ñ
Ñ
011
OP3
OP3
Ñ
OP3
Ñ
Ñ
Ñ
Ñ
100
OP4
Ñ
Ñ
Ñ
OP4
Ñ
Ñ
Ñ
101
OP5
OP5
Ñ
Ñ
Ñ
OP5
Ñ
Ñ
110
OP6
Ñ
OP6
Ñ
Ñ
Ñ
OP6
Ñ
111
OP7
OP7
Ñ
OP7
Ñ
Ñ
Ñ
OP7
Half Word
(0010)
000
OP0
OP1
Ñ
Ñ
Ñ
Ñ
Ñ
Ñ
001
OP1
OP1
OP2
Ñ
Ñ
Ñ
Ñ
Ñ
010
OP2
OP3
OP2
OP3
Ñ
Ñ
Ñ
Ñ
100
OP4
OP5
Ñ
Ñ
OP4
OP5
Ñ
Ñ
101
OP5
OP5
OP6
Ñ
Ñ
OP5
OP6
Ñ
110
OP6
OP7
OP6
OP7
Ñ
Ñ
OP6
OP7
Triple Byte
(0011)
000
OP0
OP1
OP2
Ñ
Ñ
Ñ
Ñ
Ñ
001
OP1
OP1
OP2
OP3
Ñ
Ñ
Ñ
Ñ
100
OP4
OP5
OP6
Ñ
OP4
OP5
OP6
Ñ
101
OP5
OP5
OP6
OP7
Ñ
OP5
OP6
OP7
Word
(0100)
000
OP0
OP1
OP2
OP3
Ñ
Ñ
Ñ
Ñ
100
OP4
OP5
OP6
OP7
OP4
OP5
OP6
OP7
Double Word
(0000)
000
OP0
OP1
OP2
OP3
OP4
OP5
OP6
OP7