CY7C135 Datasheet, PDF (1/12 Pages) Cypress Semiconductor – 4K x 8 Dual-Port Static RAM and 4K x 8 Dual-Port SRAM with Semaphores

CY7C135
CY7C1342
4K x 8 Dual-Port Static RAM and 4K x 8 Dual-Port
SRAM with Semaphores
Features
Functional Description
• True Dual-Ported memory cells which allow simulta-
neous reads of the same memory location
• 4K x 8 organization
• 0.65-micron CMOS for optimum speed/power
• High-speed access: 15 ns
• Low operating power: I_CC = 160 mA (max.)
• Fully asynchronous operation
• Automatic power-down
• Semaphores included on the 7C1342 to permit software
handshaking between ports
• Available in 52-pin PLCC
The CY7C135 and CY7C1342 are high-speed CMOS 4K x 8
dual-port static RAMs. The CY7C1342 includes semaphores
that provide a means to allocate portions of the dual-port RAM
or any shared resource. Two ports are provided permitting in-
dependent, asynchronous access for reads and writes to any
location in memory. Application areas include interproces-
sor/multiprocessor designs, communications status buffering,
and dual-port video/graphics memory.
Each port has independent control pins: chip enable (CE),
read or write enable (R/W), and output enable (OE). The
CY7C135 is suited for those systems that do not require
on-chip arbitration or are intolerant of wait states. Therefore,
the user must be aware that simultaneous access to a location
is possible. Semaphores are offered on the CY7C1342 to as-
sist in arbitrating between ports. The semaphore logic is com-
prised of eight shared latches. Only one side can control the
latch (semaphore) at any time. Control of a semaphore indi-
cates that a shared resource is in use. An automatic pow-
er-down feature is controlled independently on each port by a
chip enable (CE) pin or SEM pin (CY7C1342 only).
The CY7C135 and CY7C1342 are available in 52-pin PLCC.
Logic Block Diagram
R/W_L
R/W_R
CE_L
CE_R
OE_L
OE_R
I/O_7L
I/O_0L
A_11L
A_0L
I/O
CONTROL
I/O
CONTROL
ADDRESS
DECODER
MEMORY
ARRAY
ADDRESS
DECODER
I/O_7R
I/O_0R
A_11R
A_0R
(7C1342 only) _SEM
L
CE_L
OE_L
R/W_L
SEMAPHORE
ARBITRATION
(7C1342 only)
CE_R
OE_R
R/W_R
(7C1342 only)
R
SEM
1342–1
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
Document #: 38-06038 Rev. *B
Revised June 22, 2004