CY7C056V
CY7C057V
Document #: 38-06055 Rev. ** Page 2 of 23
Functional Description
The CY7C056V and CY7C057V are low-power CMOS 16K
and 32K x 36 dual-port static RAMs. Various arbitration
schemes are included on the devices to handle situations
when multiple processors access the same piece of data. Two
ports are provided, permitting independent, asynchronous ac-
cess for reads and writes to any location in memory. The de-
vices can be utilized as standalone 36-bit dual-port static
RAMs or multiple devices can be combined in order to function
as a 72-bit or wider master/slave dual-port static RAM. An M/S
pin is provided for implementing 72-bit or wider memory appli-
cations without the need for separate master and slave devic-
es or additional discrete logic. Application areas include inter-
processor/multiprocessor designs, communications status
buffering, and dual-port video/graphics memory.
Each port has independent control pins: Chip Enable (CE
)
[3]
,
Read or Write Enable (R/W
), and Output Enable (OE). Two
flags are provided on each port (BUSY and INT). BUSY sig-
nals that the port is trying to access the same location currently
being accessed by the other port. TheInterrupt Flag (INT
) per-
mits communication between ports or systems by means of a
mail box. The semaphores are used to pass a flag, or token,
from one port to the other to indicate that a shared resource is
in use. The semaphore logic is comprised of eight shared
latches. Only one side can control the latch (semaphore) at
any time. Control of a semaphore indicates that a shared re-
source is in use. An automatic Power-Down feature is con-
trolled independently on each port by Chip Select (CE
0
and
CE
1
) pins.
The CY7C056V and CY7C057V are available in 144-Pin Thin
Quad Plastic Flatpack (TQFP) and 172-Ball Ball Grid Array
(BGA) packages.
Note:
3. CE
is LOW when CE
0
≤ V
IL
and CE
1
≥ V
IH
.
