What this synchronous dual-port SRAM does in the system
The Cypress CY7C0851AV-133AXC is a 2 Mbit synchronous dual-port SRAM organized as 64K words of 36 bits each. It provides two independent ports with separate address, data, and control lines, allowing simultaneous read/write access from two bus masters — a common requirement in shared-memory architectures for network switches, telecom line cards, and multiprocessor systems. The 133 MHz clock rate supports back-to-back pipelined transactions with zero dead cycles when arbitration is handled correctly.
133 MHz clock and 64K x 36 organization — what they mean for throughput
At 133 MHz, each port can sustain a data rate of up to 133 million 36-bit words per second, assuming no arbitration stalls. The 64K depth is typical for packet buffers in 10/100 Ethernet switches or as a shared mailbox between a control processor and a data-path ASIC. The 36-bit word width accommodates 32-bit data plus parity or sideband control, saving external logic.
No last-time-buy window remains; the surplus market is the only supply path.
The TQFP footprint is standard for high-pin-count SRAMs of this era; board layouts should account for the 24x24 mm land pattern and 0.5 mm solder paste stencil aperture.