CY7C1329
Document #: 38-05279 Rev. *B
Page 4 of 15
Introduction
Functional Overview
All synchronous inputs pass through input registers controlled
by the rising edge of the clock. All data outputs pass through
output registers controlled by the rising edge of the clock.
Maximum access delay from the clock rise (tCO) is 4.2 ns
(133-MHz device).
The CY7C1329 supports secondary cache in systems utilizing
either a linear or interleaved burst sequence. The interleaved
burst order supports Pentium and i486
processors. The
linear burst sequence is suited for processors that utilize a
linear burst sequence. The burst order is user selectable, and
is determined by sampling the MODE input. Accesses can be
initiated with either the Processor Address Strobe (ADSP) or
the Controller Address Strobe (ADSC). Address advancement
through the burst sequence is controlled by the ADV input. A
two-bit on-chip wraparound burst counter captures the first
address in a burst sequence and automatically increments the
address for the rest of the burst access.
Byte Write operations are qualified with the Byte Write Enable
(BWE) and Byte Write Select (BW[3:0]) inputs. A Global Write
Enable (GW) overrides all Byte Write inputs and writes data to
all four bytes. All writes are simplified with on-chip
synchronous self-timed Write circuitry.
Three synchronous Chip Selects (CE1, CE2, CE3) and an
asynchronous Output Enable (OE) provide for easy bank
selection and output three-state control. ADSP is ignored if
CE1 is HIGH.
Single Read Accesses
This access is initiated when the following conditions are
satisfied at clock rise: (1) ADSP or ADSC is asserted LOW, (2)
CE1, CE2, CE3 are all asserted active, and (3) the Write
signals (GW, BWE) are all deasserted HIGH. ADSP is ignored
if CE1 is HIGH. The address presented to the address inputs
(A[15:0]) is stored into the address advancement logic and the
Address Register while being presented to the memory core.
The corresponding data is allowed to propagate to the input of
the Output Registers. At the rising edge of the next clock the
data is allowed to propagate through the output register and
onto the data bus within 4.2 ns (133-MHz device) if OE is
active LOW. The only exception occurs when the SRAM is
emerging from a deselected state to a selected state, its
outputs are always three-stated during the first cycle of the
access. After the first cycle of the access, the outputs are
controlled by the OE signal. Consecutive single Read cycles
are supported. Once the SRAM is deselected at clock rise by
the chip select and either ADSP or ADSC signals, its output
will three-state immediately.
Single Write Accesses Initiated by ADSP
This access is initiated when both of the following conditions
are satisfied at clock rise: (1) ADSP is asserted LOW, and (2)
CE1, CE2, CE3 are all asserted active. The address presented
to A[15:0] is loaded into the address register and the address
advancement logic while being delivered to the RAM core. The
Write signals (GW, BWE, and BW0–BW3) and ADV inputs are
ignored during this first cycle.
ADSP triggered Write accesses require two clock cycles to
complete. If GW is asserted LOW on the second clock rise, the
data presented to the DQ[31:0] inputs is written into the corre-
sponding address location in the RAM core. If GW is HIGH,
then the Write operation is controlled by BWE and BW[3:0]
signals. The CY7C1329 provides Byte Write capability that is
described in the Write Cycle Description table. Asserting the
Byte Write Enable input (BWE) with the selected Byte Write
(BW[3:0]) input will selectively write to only the desired bytes.
Bytes not selected during a Byte Write operation will remain
unaltered. A synchronous self-timed Write mechanism has
been provided to simplify the Write operations.
Because the CY7C1329 is a common I/O device, the Output
Enable (OE) must be deasserted HIGH before presenting data
to the DQ[31:0] inputs. Doing so will three-state the output
drivers. As a safety precaution, DQ[31:0] are automatically
three-stated whenever a Write cycle is detected, regardless of
the state of OE.
Single Write Accesses Initiated by ADSC
ADSC Write accesses are initiated when the following condi-
tions are satisfied: (1) ADSC is asserted LOW, (2) ADSP is
deasserted HIGH, (3) CE1, CE2, CE3 are all asserted active,
and (4) the appropriate combination of the Write inputs (GW,
BWE, and BW[3:0]) are asserted active to conduct a Write to
the desired byte(s). ADSC triggered Write accesses require a
single clock cycle to complete. The address presented to
A[15:0] is loaded into the address register and the address
advancement logic while being delivered to the RAM core. The
ADV input is ignored during this cycle. If a global Write is
conducted, the data presented to the DQ[31:0] is written into the
corresponding address location in the RAM core. If a Byte
Write is conducted, only the selected bytes are written. Bytes
not selected during a Byte Write operation will remain
unaltered. A Synchronous self-timed Write mechanism has
been provided to simplify the Write operations.
Because the CY7C1329 is a common I/O device, the Output
Enable (OE) must be deasserted HIGH before presenting data
to the DQ[31:0] inputs. Doing so will three-state the output
drivers. As a safety precaution, DQ[31:0] are automatically
three-stated whenever a Write cycle is detected, regardless of
the state of OE.
Burst Sequences
The CY7C1329 provides a two-bit wraparound counter, fed by
A[1:0], that implements either an interleaved or linear burst
sequence. The interleaved burst sequence is designed specif-
ically to support Intel Pentium applications. The linear burst
sequence is designed to support processors that follow a
linear burst sequence. The burst sequence is user selectable
through the MODE input.
Asserting ADV LOW at clock rise will automatically increment
the burst counter to the next address in the burst sequence.
Both Read and Write burst operations are supported.
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