The M5M5W816WG-70HI#ST is a standard SRAM organized as 512K words by 16 bits, with a 55 ns access time. That density and speed pair it to legacy microcontroller buses and FPGA block-RAM expansion where the memory controller expects a synchronous or asynchronous SRAM interface — not a serial flash or EEPROM. At 512Kx16, this part delivers 8 Mbit of volatile storage. The 55 ns access time means it can keep up with bus clocks up to roughly 18 MHz without wait states, assuming the bus timing budget accounts for the address-to-data propagation through the board traces.
Active production — still a current BOM line
Bulk packaging means the parts ship loose in a tube or tray — no tape-and-reel carrier. That is typical for hand-assembly or low-volume rework, but if your pick-and-place line expects embossed tape, you will need to transfer the parts into a feeder-compatible carrier or source a taped variant.
Why the flash peers are not drop-in replacements
It cannot be dropped into a socket wired for a parallel SRAM without a board spin and firmware changes. The other two peers, ATXP032-CCUE-T and AT45DB021E-SSHNHC-T, are also serial flash devices. None share the 512Kx16 parallel SRAM footprint or the 55 ns access timing. If you need a functional second-source for this SRAM, look for another standard 512Kx16 asynchronous SRAM in the same TSOP-II or SOJ package — not a flash part.