Browse Prior Art Database

Command Transfer Path for DOS and Windows

IP.com Disclosure Number: IPCOM000105957D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Keener, DS: AUTHOR [+2]

Abstract

Disclosed is a mechanism for providing, in a system having a SCSI controller using an SCB (Subsystem Control Block) architecture for interfacing a hardfile subsystem to an operating system, and having an operating system, such as DOS or Windows*, which does not support multithreading of hardfiles, a path, operating in a manner similar to that of the conventional INT (Interrupt) 13 interface, for transferring certain commands to the SCSI subsystem.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 68% of the total text.

Command Transfer Path for DOS and Windows

      Disclosed is a mechanism for providing, in a system having a
SCSI controller using an SCB (Subsystem Control Block) architecture
for interfacing a hardfile subsystem to an operating system, and
having an operating system, such as DOS or Windows*, which does not
support multithreading of hardfiles, a path, operating in a manner
similar to that of the conventional INT (Interrupt) 13 interface, for
transferring certain commands to the SCSI subsystem.

      While the SCB architecture permits a very flexible multitasking
system, it provides no benefit in a single threading (DOS or Windows)
environment, in which the substantial overhead required to implement
the SCB architecture, with its transmission of blocks of control
information, results in a loss in performance over a system using an
INT 13 interface.

      Therefore, a low-overhead additional path, which has been
called a "FASTPATH" interface, is provided for INT 13 commands in a
system operating with DOS or Windows.  Other commands are transmitted
through the SCB interface of the SCSI controller.

      The hardware supplies a set of registers by which the system
software (BIOS) and controller microcode communicate.  These
registers, which consume eight bytes of system I/O space, include a
status field indicating when an interrupt is requested, a return code
paralleling the INT 13 return code field, a device code indicating to
which device the command is...