Funcionamento porta paralela (ingles)

Interfacing the Standard Parallel Port

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Interfacing the Standard Parallel Port
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Table of Contents
Introduction to Parallel Ports Hardware Properties Centronics? Port Addresses Software Registers - Standard Parallel Port (SPP) Bi-directional Ports Using The Parallel Port to Input 8 Bits. Nibble Mode Using the Parallel Port's IRQ Parallel Port Modes in BIOS Parallel Port Modes and the ECP’s Extended Control Register Page 1 Page 2 Page 4 Page 4 Page 6 Page 8 Page 9 Page 11 Page 12 Page 14 Page 15

Introduction to Parallel Ports
The Parallel Port is the most commonly used port for interfacing home made projects. This port will allow the input of up to 9 bits or the output of 12 bits at any one given time, thus requiring minimal external circuitry to implement many simpler tasks. The port is composed of 4 control lines, 5 status lines and 8 data lines. It's found commonly on the back of your PC as a D-Type 25 Pin female connector. There may also be a D-Type 25 pin male connector. This will be a serial RS-232 port and thus, is a totally incompatible port. Newer Parallel Port’s are standardized under the IEEE 1284 standard first released in 1994. This standard defines 5 modes of operation which are as follows, 1. Compatibility Mode. 2. Nibble Mode. (Protocol not Described in this Document) 3. Byte Mode. (Protocol not Described in this Document) 4. EPP Mode (Enhanced Parallel Port). 5. ECP Mode (Extended Capabilities Port). The aim was to design new drivers and devices which were compatible with each other and Interfacing the Standard Parallel Port Page 1

Interfacing the Standard Parallel Port

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also backwards compatible with the Standard Parallel Port