Browse Prior Art Database

Generic BIOS Interrupt 13 Driver for Direct Access Storage Device

IP.com Disclosure Number: IPCOM000113709D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 124K

Publishing Venue

IBM

Related People

Berkoff, RA: AUTHOR

Abstract

Disclosed is a method to load and run the OS/2* Operating System on a computing system having DASD devices whose hardware interfaces are not known, for which custom multi-tasking device drivers are not available.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Generic BIOS Interrupt 13 Driver for Direct Access Storage Device

      Disclosed is a method to load and run the OS/2* Operating
System on a computing system having DASD devices whose hardware
interfaces are not known, for which custom multi-tasking device
drivers are not available.

      The vast majority of suppliers of DASD controllers have
tailored their products to be DOS compatible.  At a first level of
compatibility, controllers are compatible at the hardware register
level with the original PC AT* (WD-1003) type controllers.  The
controllers of Integrated Drive Electronics (IDE) drives are examples
of this kind of compatibility.  At a second level of compatibility,
controllers have BIOS compatibility, since the controller
manufacturer has defined a hardware register interface maintaining
DOS compatibility by including a BIOS ROM on the controller card.
Sometimes this register is proprietary.  This ROM translates software
BIOS INT 13 requests to controller register interface commands.  Most
SCSI controllers provide compatibility only at the BIOS level.

      To provide support for a wide variety of DASD controllers from
various manufacturers, it is necessary to use the INT 13 BIOS support
provided by almost all such manufacturers.  Specifically, for
operation in a multi-tasking environment, a V86 (Virtual i8086**)
mode environment is required to make BIOS operate properly.  Also,
I/O request queuing services are needed, so that the operating system
can continue to run in a multi-tasking mode.  Furthermore, interface
translation services are needed to convert operating system requests
to
BIOS INT 13 requests, and to provide serialization for requests to
BIOS.

      These functions are provided as schematically shown in the
Figure.  The OS/2 File Systems 1 view a Generic BIOS INT 13 Driver 2
as any other Protected Mode DASD device driver written to OS/2
specifications.  In this way, a need to modify OS/2 File Systems is
avoided.

      During initialization, the Generic BIOS INT 13 Driver 2
determines whether BIOS-supported drives exist that are not
recognized by the existing DASD drivers.  This is accomplished either
by issuing BIOS INT 13 requests to drive IDs 80-8x to see if they
respond, or alternately by checking BIOS fields in low memory.  By
convention, drives supporting the PC AT (WD-1003) interface always
have priority, getting lower IDs.  These drives are supported by the
OS/2 Protected Mode Drivers.  The Generic INT 13 Driver determines
the number of drives supported by the existing Protected Mode Driver
and support those drives which do not have full OS/2 support.

      If G...