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Browse Prior Art Database

SCSI Disk Advanced BIOS Software LED

IP.com Disclosure Number: IPCOM000100790D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 71K

Publishing Venue

IBM

Related People

Geisler, DR: AUTHOR [+2]

Abstract

This article describes a technique for use in a personal computer system which synchronizes access to a light-emitting diode (LED) control port and ensures that it is programmed to the correct state.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 60% of the total text.

SCSI Disk Advanced BIOS Software LED

       This article describes a technique for use in a personal
computer system which synchronizes access to a light-emitting diode
(LED) control port and ensures that it is programmed to the correct
state.

      Small computer system interface (SCSI) disk advanced basic
input output system (ABIOS) supports any combination of adapters in a
system up to a total of 4.  It also supports up to 15 disk devices
on each adapter, yielding a total of up to 60 devices, all of which
may be accessed in an overlapped fashion.  Assuming that the
fixed-disk activity LED is in an off state and there are no
outstanding disk requests, a request is made to access a disk
(henceforth referred to as the first disk) and the fixed-disk
activity LED is programmed to the 'on' state.  While the request is
being processed by the first disk, a request is made to a different
disk (henceforth referred to as the second disk). The request is sent
to the second disk, and the fixed-disk activity LED remains on.  An
interrupt occurs for the re quest to the first disk indicating
command complete.  The fixed-disk activity LED is programmed to the
off state. However, there is still an outstanding disk request for
which the LED should be on.

      The technique disclosed herein creates an LED array with an
entry on each device.  Access to a specific element in the array is
through the combination of adapter number and device number on the
adapter.  In eff...