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Xref: sserve comp.edu:4221 comp.edu.composition:700 comp.graphics:27780 comp.graphics.animation:2985 comp.graphics.visualization:3043 comp.human-factors:4460 comp.lang.c:43825 comp.lang.c++:37662 comp.lang.misc:9545 comp.multimedia:6142 comp.os.386bsd.development:724 comp.os.386bsd.misc:336 comp.os.ms-windows.advocacy:6738 Newsgroups: comp.edu,comp.edu.composition,comp.graphics,comp.graphics.animation,comp.graphics.visualization,comp.human-factors,comp.lang.c,comp.lang.c++,comp.lang.misc,comp.multimedia,comp.os.386bsd.development,comp.os.386bsd.misc,comp.os.ms-windows.advocacy Path: sserve!newshost.anu.edu.au!munnari.oz.au!spool.mu.edu!howland.reston.ans.net!usc!elroy.jpl.nasa.gov!decwrl!netcomsv!netcom.com!abig From: abig@netcom.com (Access Bus Industry Gp) Subject: ACCESS.bus (Re: ACCESS.bus Software Creator's Contest) Message-ID: <abigC6vz21.HHF@netcom.com> Followup-To: abig@netcom.com Organization: NETCOM On-line Communication Services (408 241-9760 guest) Date: Tue, 11 May 1993 23:39:36 GMT Lines: 92 Intro to ACCESS.bus (RE: the ACCESS.bus Software Creator's Contest Announcement) WHAT IS ACCESS.bus? ACCESS.bus is a new open industry standard for computer peripheral connectivity. ACCESS.bus is a serial protocol that uses simple, low-cost I2C technology to link multiple devices to a single PC port. Peripheral devices such as keyboards or keypads, locators (Mice, Trackballs, Joysticks), printers, VR gloves, digitizers, sensors, actuators or data transmitters and others can be easily daisy chained to the host PC. Applications such as CAD/CAM, Data Acquisition, Simulation, Virtual Reality, Multiple-Player/Single PC Games, Education and many, many more can now take advantage of ACCESS.bus, the technology that puts Plug and Play on every PC. The ACCESS.bus offers advantages to end-users and developers of systems and peripherals. Multiple devices connect to the host computer with only one port. Common communication methods for a number of device types lead to simplified hardware and software development. As an open standard, ACCESS.bus enables cross- platform use of the same device. ACCESS.bus TECHNOLOGICAL DESCRIPTION: ===================================== ACCESS.bus technology is an open specification, enabling anyone to implement it on host systems or in peripheral devices without fee or royalty. ACCESS.bus has a bus topology architecture. That is, a single host can accommodate up to 125 peripheral devices. ACCESS.bus data rate is 100 Kbits/sec. ACCESS.bus Physical Layer ^^^^^^^^^^^^^^^^^^^^^^^^^ ACCESS.bus is a serial bus architecture, based on I2C hardware protocol, with one data line and one clock line. Standard low-cost I2C microcontrollers handle bit-level handshaking, including automatic arbitration and clock synchronization. ACCESS.bus Software Protocols ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The ACCESS.bus communication protocol is composed of three levels: I2C Protocol, Base Protocol, and Application Protocol. I2C PROTOCOL: This simple and efficient protocol defines arbitration among contending masters without losing data. I2C provides for cooperative synchronization of bus partners with different clock rates. Bus transactions include addressing, framing of bits into bytes, and byte acknowledgment by the receiver. BASE PROTOCOL: Establishes the asymmetrical interconnect between a host computer and multiple peripherals. The host becomes the ACCESS.bus manager. The Base Protocol defines the format of an ACCESS.bus message envelope, which is an I2C bus transaction with additional semantics, including checksum. Unique features of the Base Protocol are auto-addressing and hot plugging. Auto-addressing assigns devices with unique bus addresses, without the need for setting jumpers or switches. Hot plugging is the ability to attach and detach devices while the system is running, without rebooting. APPLICATION PROTOCOL: This is the highest level of the ACCESS.bus protocol which defines message semantics specific to particular types of devices. Each type requires a different Application Protocol. Three broad device types have been identified: keyboards, locators, and text devices. ACCESS.bus support on the PC ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ All three levels of the ACCESS.bus protocol are supported on the PC. An add-on card implements the physical layer and uses the base protocol to communicate with physical ACCESS.bus devices. An ACCESS.bus Manager - TSR under DOS and a DLL under Windows 3.1 - controls the operation of the physical layer and interacts with the ACCESS.bus device drivers. Drivers are available for multiple ACCESS.bus keyboards, locators and printers for DOS and Windows 3.1. Also available are C language source code examples of the interface from applications to the device drivers. To Contact ABIG (the ACCESS.bus Industry Group): ------------------------------------------------ Postal Address: 370 Altair Way, Suite 215, Sunnyvale, CA 94086 Internet Email: abig@netcom.com Fax: (408) 991-3773 Voice: (408) 991-3517