LSI53C875 LSI Logic, LSI53C875 Datasheet - Page 104

• Manufacturer Part Number: LSI53C875
• Description: PCI to Ultra SCSI I/O Processor
• Manufacturer: LSI Logic

Table 4.5
Table 4.6
4-12
Name
PAR
BYTEPAR[3:0]
(LSI53C875N
only)
Name
FRAME/
TRDY/
LSI53C875JB
LSI53C875N,
LSI53C875J,
LSI53C875,
Address and Data Signals (Cont.)
Interface Control Signals
19/25/G3
16/22/F2
Pin No.
LSI53C875,
LSI53C875J: 25
LSI53C875N: 31
LSI53C875JB: H1
193, 8, 34, 47
Table 4.6
Signal Descriptions
Pin No.
S/T/S Cycle Frame is driven by the current master to indicate the
S/T/S Target Ready indicates the target agent’s (selected device’s)
Type
describes the Interface Control Signals group.
Description
beginning and duration of an access. FRAME/ is asserted to
indicate a bus transaction is beginning. While FRAME/ is
asserted, data transfers continue. When FRAME/ is deasserted,
the transaction is in the final data phase or the bus is idle.
ability to complete the current data phase of the transaction.
TRDY/ is used with IRDY/. A data phase is completed on any
clock when both TRDY/ and IRDY/ are sampled asserted. During
a read, TRDY/ indicates that valid data is present on AD[31:0].
During a write, it indicates the target is prepared to accept data.
Wait cycles are inserted until both IRDY/ and TRDY/ are asserted
together.
T/S
Typ
T/S
e
Description
Parity is the even parity bit that protects the AD[31:0]
and C_BE[3:0]/ lines. During address phase, both the
address and command bits are covered. During data
phase, both data and byte enables are covered.
When the PCI Byte Parity pins are enabled, the
LSI53C875N checks each byte of incoming data on the
PCI bus against its corresponding parity line, in
addition to the normal parity checking against the PCI
PAR signal. This extra parity checking/generation is
always enabled for the LSI53C875N. Is not register
selectable. A parity error on any Byte Parity pin for PCI
master read or slave write operation causes a fatal
DMA interrupt and SCRIPTS stops running. Mask this
interrupt with the Extended Byte Parity Enable bit, bit 1
of the
DMA Interrupt Enable (DIEN)
register.