Chapter 4 IEEE 1284 Parallel Interface
Table 9. IEEE 1284 Signals
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Pin | Source of Data |
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Compatible | Nibble | Byte | |||
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26 |
| Signal Ground (Data 7) |
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27 |
| Signal Ground (Data 8) |
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28 |
| Signal Ground (PError, Select, nAck) | |||
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29 |
| Signal Ground (Busy, nFault) |
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30 |
| Signal Ground (nAutoFd, nSelectIn, nInit) | |||
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31 | Host | nInit |
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32 | Printer | NFault | nDataAvail | aDataAvail | |
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33 |
| Not Defined |
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34 |
| Not Defined |
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35 |
| Not Defined |
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36 | Host | nSelectIn | 1284 Active | 1284 Active | |
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NOTE: The length of the data cable from the host computer to the printer should not exceed 10 meters (32 feet).
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
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
Host Busy / Host Acknowledge / NDStrobe. Driven by the host. Activates
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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