12 ns async SRAM in a 44-TSOP II — what you're getting
The Cypress CY7C1021BNV33L-12ZXCT is a 1Mbit asynchronous SRAM organized as 64K x 16 bits, with a 12 ns access time that matches the write cycle time.
Obsolete — the sourcing picture
That means the only supply channel is surplus inventory or broker stock — no factory orders, no last-time-buy window. If you have an active BOM line with this code, you are looking at the independent distribution market.
12 ns access time — the bus-timing decision
The 12 ns access time is the headline spec here. For a 66 MHz bus (15 ns cycle), this part gives you about 3 ns of margin before the host has to insert a wait state. If your controller runs at 100 MHz (10 ns cycle), you will need to account for board trace delay and output loading — the 12 ns figure is measured at the datasheet's test load, not on your PCB. Budget another 2–3 ns for capacitive derating if the bus fans out to multiple loads.
No level-shifting needed if your host logic runs at the same voltage. The 12 ns write cycle time is symmetric with the read access, so back-to-back transactions at full speed are possible — no dead cycles for bus-turnaround, which matters for high-throughput data buffers.