This standard defines two levels of device compliance.
a) A IEEE 1284-I compliant device shall have a mechanical interface using IEEE 1284-A and IEEE 1284-B connectors, have a Level 1 electrical interface, and abide with the protocol compliance criteria, all of which are listed below.
b) A IEEE 1284-II compliant device shall have a mechanical interface using IEEE 1284-C connectors, have a Level 2 electrical interface, and abide with the protocol compliance criteria, all of which are listed below.
IEEE 1284 devices shall use IEEE 1284-A, IEEE 1284-B, or IEEE 1284-C connectors in one of the config-urations depicted in clause 8. The IEEE 1284-C connectors are recommended for all new designs.
Level 1 electrical requirements provide sufficient margin to assure operation with any compatible or Level 1 compliant device. See 8.3.2 for a complete list of requirements.
Level 2 requirements ensure that all IEEE 1284 Level 2 compliant devices will interoperate with any IEEE 1284 Level 2 compliant device and in general with IEEE 1284 Level 1 compliant devices. See 8.3.3 for a complete list of requirements.
It is recommended that all new designs implement Level 2 drivers and receivers.
Compliant devices shall implement Compatibility (SPP)and Nibble Modes as defined within this standard, as well as the negotiation phases necessary to transition between these two modes. Implementation of Byte, ECP, and/or EPP Modes (also defined within this standard) is recommended but not required for IEEE 1284 compliance.
Peripherals may, but are not required to, implement the Device ID string as specified in 7.6. Peripherals that implement the Device ID string shall be able to return the ID string to the host in the Nibble Mode. It is rec-ommended that peripherals be able to return the ID string to the host using any of the reverse channel modes implemented by the device with the exception of EPP.
Interconnection cables intended for use with IEEE 1284 devices shall meet the mechanical and electrical requirements of clause 8. Cable assemblies that meet these requirements shall be clearly and permanently labeled “IEEE Std 1284-1994 compliant” to distinguish them from cables having the same type connectors but different electrical characteristics.