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Timer-Based Device Configurator

IP.com Disclosure Number: IPCOM000034519D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 4 page(s) / 231K

Publishing Venue

IBM

Related People

Van Heuklon, JJ: AUTHOR [+4]

Abstract

A process allows displays and printers to be turned on at any time without pre-configuring them and without having to re-IPL the system. Messages are sent to the host any time that a device powers on or off. The host system specifies when to start polling for unconfigured devices and when to stop. The rate at which new devices are polled is dependent on how many powered-up devices are already up. The configurator function is performed by initiating autopoll to one device at a time. Autopoll means that the device is polled by the hardware once every 15 - 20 milliseconds. When autopoll is initiated for a device, a software timer is set. If the autopoll function detects that the device is powered on before the timer expires, then the device is made available to the host system.

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Timer-Based Device Configurator

A process allows displays and printers to be turned on at any time without pre- configuring them and without having to re-IPL the system. Messages are sent to the host any time that a device powers on or off. The host system specifies when to start polling for unconfigured devices and when to stop. The rate at which new devices are polled is dependent on how many powered-up devices are already up. The configurator function is performed by initiating autopoll to one device at a time. Autopoll means that the device is polled by the hardware once every 15 - 20 milliseconds. When autopoll is initiated for a device, a software timer is set. If the autopoll function detects that the device is powered on before the timer expires, then the device is made available to the host system. If the timer expires first, then that device is assumed to be powered off, and autopoll is stopped for that device. Autopoll is then started for the next device, along with a timer. The value of the timer is dependent on the number of devices not currently powered up, so that each station not powered up is autopolled once every 10 seconds regardless of the number of devices being "slow-polled". This method improves performance because devices which are not yet powered on are polled much less often. Devices which are powered on are polled more often because the user may be pressing keys, which must be detected as soon as possible. When the host sends the comman...