The present invention discloses a
system for buffering the outputs of
peripheral devices operating in UTOPIA protocol to allow devices on separate circuit boards connected through long buses, such as backplanes, to communicate with the
system controller. Address detection logic stores the
peripheral device address and compares it to the UTOPIA
bus address
signal. When the correct address is recognized in a first
clock cycle, a
flip flop stores the information for the next cycle. A second
flip flop stores the state of the read enable
signal. An
AND gate detects when the correct address was found and the read enable was de-asserted during the first
clock cycle and the read enable and read
cell available signals are positive during the current
clock cycle and provides a high
signal to a third
flip flop. On a third clock cycle the third flip flop enables the outputs of a
data buffer which then drives the
peripheral device data signals on to the read data
bus. The third flip flop output and the read enable signal are provided to a second
AND gate which feeds back to the third flip flop to maintain its state until the read enable signal is de-asserted. The first flip flop is also used to control a buffer for the read
cell available signal from the peripheral device. The third flip flop is also used to control a buffer for the read start of
cell signal from the peripheral device.