Bidirectional first-in-first-out memory device with transparent and

Abstract

A multi-featured first-in-first-out (FIFO) memory device on a monolithic semiconductor integrated circuit chip. The FIFO device is bi-directional, in that the user may select the direction of data transfer through the device. The device may be configured in a transparent bypass mode of operation, wherein the FIFO memory array is bypassed, and data is transferred directed from either device input/output port to the other device input/output port. In another mode of operation allowing registered bypass operation, a byte of data may be written in an internal register from the device port being used to output data for later transfer to the device port presently being used to input data to the FIFO memory array. The FIFO device further includes a user-testable mode of operation, wherein data written into the FIFO memory array through a device input port may be read out of the same device input port. Device mode selection occurs through control pin slew detection, allowing mode selection with a minimum number of control pins.