The CY7C419, CY7C420/1, CY7C424/5, CY7C428/9, and CY7C432/3 are first-in first-out (FIFO) memories offered in 600-mil wide and 300-mil wide packages. There are 256, 512, 1,024, 2,048, and 4,096 words respectively by 9 bits wide. Each FIFO memory is organized such that the data is read in the same sequential order that it was written. Full and empty flags are provided to prevent overrun and underrun. Three additional pins are also provided to facilitate unlimited expansion in width, depth, or both. The depth expansion technique steers the control signals from one device to another in parallel. This eliminates the serial addition of propagation delays, so that throughput is not reduced. Data is steered in a similar manner. The read and write operations may be asynchronous; each can occur at a rate of 50 MHz. The write operation occurs when the write (W) signal is LOW. Read occurs when read (R) goes LOW. The nine data outputs go to the high impedance state when R is HIGH. |