Printronix T4204 User Manual page 182

Chapter 4
IEEE 1284 Parallel Interface
Pin Source of Data
26
27
28
29
30
31 Host
32 Printer
33
34
35
36 Host
NOTE: The length of the data cable from the host computer to the printer
Host Clock / nWrite. Driven by host. Data transferred from host to printer.
When printer sends data, two types are available. If Nibble Mode, signal is set
high. If Byte Mode, signal is set low.
Data 1 through Data 8. These pins are host-driven in Compatibility Mode and
bidirectional in Byte Mode. They are not used in Nibble Mode. Data 1 is the
least significant bit; Data 8 is the most significant bit.
Printer Clock / Peripheral Clock / Interrupt. Driven by the printer. A signal
from the printer indicating the character or function code has been received
and the printer is ready for the next data transfer.
Printer Busy / Peripheral Acknowledge / nWait. Driven by the printer.
Indicates the printer cannot receive data. (Data bits 4 and 8 in Nibble Mode.)
Acknowledge Data Request / nAcknowledge Reverse. Driven by the
printer. Indicates the printer is in a fault condition. (Data bits 3 and 7 in Nibble
Mode.)
Xflag. Driven by the printer. A high true level indicating the printer is ready for
data transfer and the printer is on-line. (Data bits 2 and 6 in Nibble Mode.)
Host Busy / Host Acknowledge / NDStrobe. Driven by the host. Activates
auto-line feed mode.
Peripheral Logic High. Driven by the printer. When the line is high, the
printer indicates all of its signals are in a valid state. When the line is low, the
printer indicates its power is off or its signals are in an invalid state.
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Table 9. IEEE 1284 Signals
Type of Mode
Compatible
Signal Ground (Data 7)
Signal Ground (Data 8)
Signal Ground (PError, Select, nAck)
Signal Ground (Busy, nFault)
Signal Ground (nAutoFd, nSelectIn, nInit)
nInit
NFault nDataAvail
Not Defined
Not Defined
Not Defined
nSelectIn 1284 Active
should not exceed 10 meters (32 feet).
Nibble Byte
aDataAvail
1284 Active