
IBM25CPC710AB3A100
IBM Dual Bridge and Memory Controller
Page 16 of 208
dbamc01_ch2.fm.01
July 13, 2000
2.1 Signal Descriptions
Tri-state driver/receivers interface 3.3 V internal functions with 3.3 V LVTTL off-chip buses. Some receivers
interface 3.3 V internal functions with either 3.3 V LVTTL or 5.0 V TTL off-chip bidirectional buses. All drivers
are 50 ohm, source-terminated. In the following table, "Pull-up" in the Type column indicates an internal pull-
up is built into the device driver/receiver. No additional external device is required.
Table 3: 60x Bus Interface Signals
(Page 1 of 3)
Signal Name
I/O
Type
Description
Address Bus Arbitration Signals
SYS_BR0
SYS_BR1
SYS_BR2
SYS_BR3
SYS_BG0
SYS_BG1
Address Transfer Start Signals
I
5.0V-tolerant
pull-up
Bus Request.
Indicates the device on the 60x bus associated with this signal is
requesting ownership of the address bus.
Note: SYS_BR2 and SYS_BR3 are reserved for future use. They should be tied
to up level (=1).
O
Bus Grant.
Indicates the master associated with this signal may, with proper
qualification, assume mastership of the address bus.
SYS_TS
I/O
Transfer Start.
Output:
Indicates device has started an address tenure and the
address bus and transfer attribute signals are valid. Only
“
address only
operations
”
and
“
snoop operation with programmable TT code
”
are per-
formed.
Input:
Indicates a master on the 60x has started an address tenure and
the address bus and transfer attribute signals are valid. For address
tenures that require a data transfer, this signal also indicates a request
for the data bus.
Address Bus Signals
SYS_ADDR[0:31]
I/O
Pull-up
Address Bus.
Output:
Represents the physical address of a cache operation that
should be snooped by devices on the 60x bus. A[0] is the most signifi-
cant address bit.
Input
: Represents the physical address for the current transaction
(except for the XferData transaction types).
Address Parity.
Output:
Represents one bit of odd parity for each of the four bytes of
the address bus. Odd parity means that an odd number of bits, includ-
ing the parity bit, are driven high. The signal assignments correspond to
the following:
AP[0] - A[0:7] AP[1] - A[8:15]
AP[2] - A[16:23] AP[3] - A[24:31]
Input:
Represents one bit of odd parity for each of the four bytes of the
address bus. A checkstop is generated if bad parity is detected and bit
8 is
‘
1
’
in the error control register.
Configuration.
Indicate the current address tenure is a configuration cycle to
the device associated with this signal. The associated device must respond (if
present) to addresses in the range
‘
FF20 0000
’
through
‘
FF20 1FFF.
’
Other
addresses are responded to as normal.
SYS_ADDRP[0:3]
I/O
Pull-up
SYS_CONFIG0
SYS_CONFIG1
O
Transfer Attribute Signals
SYS_TT[0:4]
I/O
Pull-up
Transfer Type.
Output:
Indicates the type of transfer in progress. The values are pro-
grammable according to the PowerPC type and stored in the ATAS
register.
Input
: Indicates the type of transfer in progress.