Browse Prior Art Database

Direct Access Storage Device/Small Computer Systems Interface Device Support for OS/2

IP.com Disclosure Number: IPCOM000113482D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27

Publishing Venue

IBM

Related People

Berkoff, RA: AUTHOR

Abstract

Disclosed is a set of software programming I/O interfaces which provide a uniform interface across several DASD device types. These interfaces allow the portability of existing OS/2* peripheral device drivers written to the SCSI.SYS specification of IBM, to the ASPI (Advanced SCSI Programming Interface) specification of Adaptec, or to other specifications, to SCSI host adapters built by various manufacturers. These interfaces further define a flexible "filter" mechanism to allow unique device support and additional subsystems, such as encryption and data stripping.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 28% of the total text.

Direct Access Storage Device/Small Computer Systems Interface Device
Support for OS/2

      Disclosed is a set of software programming I/O interfaces which
provide a uniform interface across several DASD device types.  These
interfaces allow the portability of existing OS/2* peripheral device
drivers written to the SCSI.SYS specification of IBM, to the ASPI
(Advanced SCSI Programming Interface) specification of Adaptec, or to
other specifications, to SCSI host adapters built by various
manufacturers.  These interfaces further define a flexible "filter"
mechanism to allow unique device support and additional subsystems,
such as encryption and data stripping.

      This method supports a base of existing SCSI peripheral device
drivers for devices, such as TAPE and CDROM, by means of installable
conversion modules, or Device Managers, which translate client system
protocols into the protocols of this architecture.  A Device Manager
is an OS/2 device driver which interfaces with other OS/2 device
drivers, with OS/2 installable file systems, or with the OS/2 Kernel.
Usually, the conversions required are relatively simple.  This method
provides a comprehensive DASD solution, including diskette devices,
including support for hybrid devices, such as diskette drives
attached to a SCSI interface along with standard diskette devices.
The involvement of the OS/2 Kernel in the implementation of I/O
drivers is minimized.  The filter mechanism allows the hiding and
reordering of hardware devices by subsystems, without using complex
data structures, such as calldown stacks, or registration protocols.

      This programming interface compartmentalizes the DASD device
driver modules into hardware-dependent and hardware-independent
components.  A hardware-independent module can be dynamically linked
with hardware-dependent modules for a given workstation
configuration.  The hardware manufacturer or vendor is required only
to develop device support to drive his unique device interface.

      A "base" device driver, through which OS/2 boots, is needed
when this operating system starts.  A base device driver is loaded
through the use, in the "CONFIG.SYS" file, of the "BASEDEV" keyword,
having the syntax BASEDEV = filename, followed by arguments, as shown
in Fig. 1.  This "BASEDEV=" statement must not contain either drive
or path information.  To find the file, the root directory of the
startup partition is first searched, followed by the \OS2 directory
of the startup partition.  Statements are processed in an order
reflecting the extension of the filename, in accordance with the
sequence ".SYS," " .BID," ".VSD," ".TSD," ".ADD," ".I13," ".FLT," and
".DMD," with ".SYS" being processed first, while ".DMD" is processed
last.

      An ADD is an OS/2 adapter device driver written in accordance
with this description.  Adapter device drivers either provide
hardware-dependant services for an adapter supplied by an OEM

(Original Equipmen...