Canon BJC 6000 - Color Inkjet Printer Service Manual page 44

Part 2: Product Specifications
Data Avail (Output)
In the reverse data transmission phase, this signal serves as bit 0 and bit 4 of data
to be sent. During negotiation, this signal tells the host computer whether or not
reverse transmission data is available. This signal is output in synchronization
with the "H"-to-"L" falling edge of Ack Data Req, which defines the timing for
notifying the availability of reverse transmission data.
1284 Active (Input)
This signal is used to confirm if the printer is 1284-compatible. Check is done
when this signal is "H" and Host Busy is "L." This signal goes "L" in the
termination phase.
ECP Mode:
Host Clk (Input)
When data is sent from the host computer to the printer, this signal and Periph
Ack perform handshaking. The host computer makes this signal "L" to notify that
it has output data onto the data bus (Data 1-8). This signal goes "H" in response to
the rising edge of Periph Ack. This signal is always "H" in the reverse data
transmission phase.
Data 1-8 (Input/Output)
These signals are input signals when data is sent from the host computer to the
printer. In the reverse data transmission phase, these signals are output signals
send data from the printer to the host computer over this data bus.
Periph Clk (Output)
This signal is always "H" when data is sent from the host computer to the printer.
In the reverse data transmission phase, this signal goes "L" to notify that data has
been output to the host computer. This signal goes "H" in response to the "L"-to-
"H" rising edge of Host Ack from the host computer.
Periph Ack (Output)
When data is to be sent from the host computer to the printer, the printer makes
this signal "L" if it is ready to receive data. The printer makes this signal "H" after
it has received the data. In the reverse data transmission phase, this signal is
used to tell whether the data the printer has output on the data bus is command
or data ("L" means command and "H," data).
Ack Reverse (Output)
This signal is always "H" when data is sent from the host computer to the printer.
In the reverse data transmission phase, this signal is always "L." When the host
computer notifies the printer that the forward data transmission phase is to
change to the reverse data transmission phase by making Reverse Req "L," the
printer acknowledges the notification by making this signal "L." Likewise, when
the host computer notifies the printer that the reverse data transmission phase is
to change to the forward data transmission phase by making Reverse Req "H," the
printer acknowledges the notification by making this signal "H."
X flag (Output)
This signal is always "H" in ECP mode.
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BJC-6000