Reference Data about the Parallel Port

Overview

The information provided here is limited to the minimum. More information (e.g.: introductions, description of parallel port etc.) can be found on Internet. Some interesting sites are listed on the "Links" page.

Port Addresses:

Name	Base Address	alternative Base Address
LPT1	0x0378	0x03BC
LPT2	0x0278	0x0378
LPT3	0x03BC	none

Port Register

Register	Direction	Address	Mask
Data Register	Input/Output	Base Address	0xFF
Status Register	Input	Base Address + 1	0xF8
Control Register	Output	Base Address + 2	0x0F

Remarks:

• Other registers ( e.g.: ECP or EPP ) are not used by ParaPort.
• The mask is defined by binary OR on the 'Bit Mask' value in the following table.
• The parallel port has 8 bit input and output, 5 bit input and 4 bit output.

Port Register and Connector Pins:

Register	Bit Number	Bit Mask	Functionality Name	Inverted	Pin
Data Register	0	0x01	Bit 0 of data byte	No	2
Data Register	1	0x02	Bit 1 of data byte	No	3
Data Register	2	0x04	Bit 2 of data byte	No	4
Data Register	3	0x08	Bit 3 of data byte	No	5
Data Register	4	0x10	Bit 4 of data byte	No	6
Data Register	5	0x20	Bit 5 of data byte	No	7
Data Register	6	0x40	Bit 6 of data byte	No	8
Data Register	7	0x80	Bit 7 of data byte	No	9
Status Register	3	0x08	Error	No	15
Status Register	4	0x10	Select	No	13
Status Register	5	0x20	PaperEnd	No	12
Status Register	6	0x40	Acknowledge	No	10
Status Register	7	0x80	_Busy	Yes	11
Control Register	0	0x01	_Strobe	Yes	1
Control Register	1	0x02	_LineFeed	Yes	14
Control Register	2	0x04	Initialize	No	16
Control Register	3	0x08	_SelectIn	Yes	17

Remarks:

• Some Pins are inverted on the connector. To set the pin to logical high TTL ( 5 Volt ), you must clear the correspondent bit. To show this, the functionality name has an underscore.

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