Electrical computers and digital processing systems: support – Digital data processing system initialization or configuration
Reexamination Certificate
1995-11-13
2002-03-12
Banankhah, Majid A. (Department: 2151)
Electrical computers and digital processing systems: support
Digital data processing system initialization or configuration
Reexamination Certificate
active
06357000
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the field of operating systems and, more particularly, to a method and system for user-specified loading of an operating system.
BACKGROUND OF THE INVENTION
A conventional computer system provides a user with the ability to run a variety of applications programs. In order to provide this feature effectively, however, such a computer system must be equipped with an operating system. As is well known in the art, an operating system provides central functions which are essential to operation of the computer system. The operating system controls the use of hardware resources necessary to run the application programs. For example, the operating system controls allocation of memory and processing time to the application programs. The fundamental portion of the operating system is a hardware-independent program, such as Microsoft's MS-DOS, OS/2, etc. When this program is implemented into a computer system, it incorporates hardware-specific code that allows it to load into that computer system and correctly control the specific hardware that is a part of that computer system. The incorporation of this hardware-specific code into the hardware-independent program provides the complete, working operating system.
An example of the conventional computer system is the personal computer system illustrated in FIG.
1
. The computer system shown in
FIG. 1
includes a microcomputer
100
, a peripheral storage device such as a disk
110
, peripheral input devices such as a keyboard
120
, a mouse
130
, etc., and peripheral output devices such as a display monitor
140
, a printer
150
, etc. The microcomputer
100
contains a central processing unit (CPU)
102
, a memory
104
and an input/output unit (I/O)
106
. An operating system, including a hardware-independent portion such as MS-DOS, OS/2, etc., as well as a hardware-specific portion, is stored in the memory
104
. The operating system contains operating system instructions which are executed by the CPU
102
. Upon execution of the operating system instructions, the operating system controls, for example, allocation of the memory
104
, allocation of processing time of the CPU
102
, and use of the peripheral devices
110
,
120
,
130
and
140
.
Typically, the operating system instructions which compose the operating system are initially stored on the disk
110
. As such, the operating system instructions must be loaded into the memory
104
before becoming operational. When a user turns on the power of the computer system or reboots the computer system (hereinafter referred to as startup), the CPU
102
first performs an initialization process which provides this function. The initialization process, in addition to performing functions such as testing and initializing the computer system hardware, loads the operating system stored on the disk
110
into the memory
104
. The operating system thereafter controls operation of the computer system to run a variety of application programs for the user.
An example of such an initialization process is the system initialization program performed by the IBM PC or by an IBM PC compatible computer system. The IBM PC is a well known computer system designed by IBM Corporation. Upon computer startup, the CPU
102
initially performs a system initialization program composed of machine-readable instructions stored in a ROM (Read Only Memory) portion of the memory
104
. The system initialization program performs, in addition to various initialization and testing functions, a conventional operating system load routine which loads operating system instructions that compose an operating system from the disk
110
into the memory
104
. Thereafter, the operating system instructions are executable by the CPU
102
to control allocation and use of the hardware.
A general flow diagram of the conventional operating system load routine is shown in FIG.
2
. In step
202
, the conventional operating system load routine (Conventional OS Load) reads a load data structure from the disk
110
into the memory
104
. The load data structure contains a partition identifier which identifies an operating system partition stored on the disk
110
. This operating system partition contains the operating system instructions which compose the operating system, as well as a set of machine readable instructions for loading those operating system instructions into the memory
104
. In step
204
, the conventional load routine reads a load record from the indicated operating system partition. The load record indicates operating system load modules stored on the operating system partition, each of which contain operating system instructions. The load record also contains load instructions for loading these operating system load modules. In step
206
, the conventional load routine loads the operating system load modules indicated by the load record by executing the load instructions in the load record, upon which the operating system load routine portion of the system initialization routine is complete.
In the conventional operating system load routine explained above, a user of the computer system has no control over the process by which the operating system load modules are loaded from the disk
110
into the memory
104
. That is, whichever operating system load modules are stored in the operating system partition and indicated by the load record stored therein are loaded into the memory
104
. As a result of this limitation, the user has no way to specify the operating system instructions which become a part of the operating system. Thus, it is impossible for the user to enhance the operating system or correct malfunctions in the operating system prior to the time the operating system is loaded by varying the operating system instructions which are loaded into memory. For example, when the hardware-specific code does not function properly or as desired, the only option conventionally has been to replace the microchip on which the system initialization program is provided with a microchip containing an updated system initialization program.
Further, it is not possible to provide such enhancements or corrections in an optional fashion. Replacement of a microchip every time a user of the computer system wishes to change a feature of the operating system is not feasible. This problem might be solved in part by providing alternate sets of operating system load modules on different partitions on the disk
110
, each set representing an alternate version of the operating system. However, such a solution has significant limitations. One limitation is that disk space is often limited on the disk on which the operating system is provided. To provide alternate versions of the operating system on different partitions would require that a large number of operating system load modules common to all versions would be redundantly stored on each version. Thus, a great deal of disk space would be wasted. Further, the conventional load record is not equipped to load an operating system from more than a limited number of partitions, or from a partition located beyond a certain location on the disk. For example, the Master Boot Record provided as the load record on conventional MS-DOS disks contains only four partition descriptors, each of which contains a single partition identifier. Thus, the Master Boot Record can reference only a limited number (4) of the partitions.
An additional problem with this approach is that the Master Boot Record contains partition identifiers of limited size, and thus cannot reference a partition with a disk address starting beyond a finite boundary (the 1024 cylinder boundary). If one or more versions of an operating system require disk space which exceeds this boundary, then no additional partitions can be referenced. As noted above, to provide alternate versions of the operating system on different partitions would require a great deal of disk space. As a result, alternate versions of the operating system are likely to be unidentifiable by the Mas
Banankhah Majid A.
Christensen O'Connor Johnson & Kindness PLLC
Lao Sne
Microsoft Corporation
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