Intel 80960HD - Manual (Page 16)

80960HA/HD/HT
16 Datasheet
Table 7. 80960Hx Processor Family Pin Descriptions (Sheet 1 of 4)
Name Type Description
A31:2
O
H(Z)
B(Z)
R(Z)
ADDRESS BUS carries the upper 30 bits of the physical address. A31 is the most
significant address bit and A2 is the least significant. During a bus access, A31:2
identify all external addresses to word (4-byte) boundaries. The byte enable
signals indicate the selected byte in each word. During burst accesses, A3 and
A2 increment to indicate successive addresses.
D31:0
I/O
S(L)
H(Z)
B(Z)
R(Z)
DATA BUS carries 32, 16, or 8-bit data quantities depending on bus width
configuration. The least significant bit of the data is carried on D0 and the most
significant on D31. The lower eight data lines (D7:0) are used when the bus is
configured for 8-bit data. When configured for 16-bit data, D15:0 are used.
DP3:0
I/O
S(L)
H(Z)
B(Z)
R(Z)
DATA PARITY carries parity information for the data bus. Each parity bit is
assigned a group of eight data bus pins as follows:
DP3 generates/checks parity for D31:24
DP2 generates/checks parity for D23:16
DP1 generates/checks parity for D15:8
DP0 generates/checks parity for D7:0
Parity information is generated for a processor write cycle and is checked for a
processor read cycle. Parity checking and polarity are programmable. Parity
generation/checking is only performed for the size of the data accessed.
PCHK
O
H(Q)
B(Q)
R(1)
PARITY CHECK indicates the result of a parity check operation. An asserted
PCHK indicates that the previous bus read access resulted in a parity check error.
BE3:0
O
H(Z)
B(Z)
R(1)
BYTE ENABLES select which of the four bytes addressed by A31:2 are active
during a bus access. Byte enable encoding is dependent on the bus width of the
memory region accessed:
32-bit bus:
BE3 enables D31:24
BE2 enables D23:16
BE1 enables D15:8
BE0 enables D7:0
16-bit bus:
BE3 becomes Byte High Enable (enables D15:8)
BE2 is not used (state is undefined)
BE1 becomes Address Bit 1 (A1)
BE0 becomes Byte Low Enable (enables D7:0)
8-bit bus:
BE3 is not used (state is undefined)
BE2 is not used (state is undefined)
BE1 Address Bit 1 (A1)
BE0 Address Bit 0 (A0)
W/R
O
H(Z)
B(Z)
R(0)
WRITE/READ is low for read accesses and high for write accesses.
W/R becomes valid during the address phase of a bus cycle and remains valid
until the end of the cycle for non-pipelined accesses. For pipelined accesses, W/
R changes state when the next address is presented.
0= Read
1= Write
D/C
O
H(Z)
B(Z)
R(0)
DATA/CODE indicates that a bus access is a data access or an instruction
access. D/C has the same timing as W/R.
0 = Code
1 = Data