A
Technical Specifications
A-7
nACK/PtrClk/PeriphClk
All modes: DATA 8 is the MSB, DATA 1 is the LSB.
Compatibility mode: Acknowledgment low pulse in order to indicate
that data was transferred from the host.
negotiation phase: Low signal indicates IEEE 1284 is supported; set
to high afterwards to indicate that theXflag and
“data available” flag are valid.
reverse data transfer phase: In nibble mode, a low signal indicates that the
nibble data is valid.
reverse idle phase: When switched from low to high, generates an
interrupt that notifies the host that there is data
available.
ECP mode: Used to transfer data from the printer to the
host with handshaking via HostAck (nAutoFd).
Busy/PtrBusy/PeriphClk
Compatibility mode: High signal indicates that the printer is not
ready to receive data.
negotiation phase: Reflects the BUSY status of the forward channel.
reverse data transfer phase: In nibble mode, this signal serves as nibble data
bit 3 and then 7.
reverse idle phase: Reflects the BUSY status of the forward channel.
ECP mode: Used for forward direction flow control. In
reverse direction, this signal is used as a ninth
data bit that indicates whether the data signals
indicate a command or data.
