Extended Capabilities Port: Specifications
Revision 1.06
July 14, 1993
Cover Letter
Important Note This may not be the first time you have received the ECP Specifications.
From time to time, Microsoft may make some modifications to the documentation and/or
software and we want to ensure that you have the latest update to the materials. If this is not the
first time you have received this kit, please read the section titled "Corrections to Previous
Versions (Revisions)" very carefully for any changes that may apply to you.
Environments such as the Microsoft® Windows™ operating system are making it easier for
anybody to use computers, and the decision to buy computers, peripherals, and software is
easier to make now that Windows provides ease of use to the personal computer (PC)
environment.
Communications with peripherals is the "Achilles heel" of the industry. Low bandwidth and lack
of bidirectionality have prevented suppliers of peripherals such as printers, scanners,
fax/modem cards, and network adapters from introducing innovative solutions. The serial port
provides bidirectionality but does not offer enough bandwidth. The standard parallel port
(Centronics
®) offers a higher but limited bandwidth and no bidirectionality. Centronics also
requires a lot of assistance from the CPU, making it inadequate for environments such as
Windows in which multiple applications are running concurrently.
The extended capabilities port (ECP) is the answer to peripheral communications problems in
the PC environment. It is a fast, bidirectional parallel interface that is backwards-compatible
with the existing PC standard parallel port configuration—and it uses the existing parallel
connectors and cables. ECP has been jointly developed by Microsoft and Hewlett-Packard with
the hopes of making it a widely adopted standard. Several chip vendors are working on
designing support for ECP into their next generation I/O chips. On the system software side,
Microsoft is building support for the full capabilities of ECP (bidirectionality, enhanced
bandwidth, enhanced protocols) into the next generation of its Windows operating
environments. A new set of application programming interfaces (APIs) will soon be available to
independent software and hardware vendors (ISVs and IHVs) to enable the writing of device
drivers and applications programs that take advantage of ECP.
Enclosed you will find the ECP Specification, which includes the following documents:
• ECP cover letter (this document).
• Extended Capabilities Port Protocol and ISA Interface Standard. Covers the ECP
signal protocols, IEEE P1284 issues, and the ISA implementation specifications. Includes
an errata sheet.
• ECP Driver Hardware Notes. Covers issues software/hardware designers must be aware
of.
• ECP Compliance Test Functional Specification. Describes the setup and use of the ECP
compliance test.
The ECP Specifications document describes in detail the ECP ISA implementation
requirements, so you do not actually need the ECP Adaptation Kit to develop an ECP ASIC or
to make ECP part of a larger chip solution. We feel, however, that having it may shorten the
time required for your ECP implementation cycle.
For additional information, please contact Doug Hogarth at 206/936-3002. Doug is a Technical
Evangelist in the Windows Developer Relations Group. If you are signing a contract, please
send it back to:
Doug Hogarth
Cover Letter
(C) 1992-1995 Microsoft Corporation. All rights reserved.
Specs: Extended Capabilities Port Pa
g
e 1 Microsoft Development Library
