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o ieee1284_parallelport o ieee1284_compatibility o ieee1284_nible o ieee1284_byte o ieee1284_epp o ieee1284_ecp o ieee1284_negotiation o ieee1284_cable o ieee1284_electrical

About Amontec

Amontec uses the power of Programmable Logic Devices (FPGA, CPLDs) to provide In-Field Programmable Products.

Chamleon POD

It can work as a true
- Raven JTAG Debug
- Wiggler JTAG Debug.
A low cost solution for debugging your ARM7 ARM9 and other processors.

Amontec Services

- VHDL Design
- VHDL Methodology
- FPGA Design
- PCB Design and Fab.
- JTAG interface
- Boundary Scan Support

Your parallel port stays a easy way for rapid prototyping. Amontec provides synchronous EPP VHDL core and synchronous ECP VHDL core (slave side). Checkout our Chameleon POD page [ieee1284] [ieee1284_parallelport] [ieee1284_compatibility] [ieee1284_nible] [ieee1284_byte] [ieee1284_epp] [ieee1284_ecp] [ieee1284_negotiation] [ieee1284_cable] [ieee1284_electrical]

IEEE 1284 Introduction ... undertand your parallel port

This section is implemented as a multilevel document. This page serves as an executive summary of the 1284 standard. By clicking on the various highlighted points, you may explore each concept in greater detail.


The recently released standard, "IEEE Std.1284-1994 Standard Signaling Method for a Bi-directional Parallel Peripheral Interface for Personal Computers", is for the parallel port what the Pentium processor is to the 286. The standard provides for high speed bi-directional communication between the PC and an external peripheral that can communicate 50 to 100 times faster than the original parallel port. It can do this and still be fully backward compatible with all existing parallel port peripherals and printers.


The SPP definition is Standard Parallel Port. (This link will give you a history and background of the parallel port and a part of the SPP specification)

The 1284 standard defines 5 modes of data transfer. Each mode provides a method of transferring data in either the forward direction (PC to peripheral), reverse direction (peripheral to PC) or bi-directional data transfer (half duplex). The defined modes are:

Forward direction only

• Compatibility Mode
• "Centronics" or standard mode

Reverse direction only

• Nibble Mode
• 4 bits at a time using status lines for data.
• Hewlett Packard Bi-tronics
• Byte Mode
• 8 bits at a time using data lines, sometimes referred to as a "bi-directional" port.

Bi-directional

• EPP
• Enhanced Parallel Port- used primarily by non-printer peripherals, CD ROM, tape, hard drive, network adapters, etc....
• ECP
• Extended Capability Port- used primarily by new generation of printers and scanners

All parallel ports can implement a bi-directional link by using the Compatible and Nibble modes for data transfer. Byte mode can be utilized by about 25% of the installed base of parallel ports. All three of these modes utilize software only to transfer the data. The driver has to write the data, check the handshake lines (i.e.: BUSY), assert the appropriate control signals (i.e.: STROBE) and then go on to the next byte. This is very software intensive and limits the effective data transfer rate to 50 to 100 Kbytes per second.

In addition to the previous 3 modes, EPP and ECP are being implemented on the latest I/O controllers by most of the Super I/O chip manufacturers. These modes use hardware to assist in the data transfer. For example, in EPP mode, a byte of data can be transferred to the peripheral by a simple OUT instruction. The I/O controller handles all the handshaking and data transfer to the peripheral.

Overall, the 1284 standard provides the following:

1. 5 modes of operation for data transfer
2. A method for the host and peripheral to determine the supported modes and to negotiate to the requested mode.
3. Defines the physical interface
• Cables
• Connectors
4. Defines the electrical interface
• Drivers/Receivers
• Termination
• Impedance

In summary, the 1284 parallel port provides an easy to use, high performance interface for portable products and printers.