DESCRIPTION:
The IDT72511 and IDT72521 are highly integrated first-in, first-out memories that enhance processor-to-processor and processor-to-peripheral communications. IDT BiFIFOs integrate two side-by-side memory arrays for data transfers in two directions.
   
FEATURES:
• Two side-by-side FIFO memory arrays for bidirectional
    data transfers
• 512 x 18-Bit - 512 x 18-Bit (IDT72511)
• 1024 x 18-Bit - 1024 x 18-Bit (IDT72521)
• 18-bit data buses on Port A side and Port B side
• Can be configured for 18-to-18-bit or 36-to-36-bit communication
• Fast 35ns access time
• Fully programmable standard microprocessor interface
• Built-in bypass path for direct data transfer between two
    ports
• Two fixed flags, Empty and Full, for both the A-to-B and
    the B-to-A FIFO
• Two programmable flags, Almost-Empty and Almost-Full
    for each FIFO
• Programmable flag offset can be set to any depth in the
    FIFO
• Any of the eight flags can be assigned to four external
    flag pins
• Flexible reread/rewrite capabilities
• Six general-purpose programmable I/O pins
• Standard DMA control pins for data exchange with
    peripherals
• 68-pin PGA and PLCC packages