Abstract: An improved data processing system and operating system having a selectable scheduler. An operating system kernel is provided having a standardized interface for permitting the installation of a selected one of multiple diverse schedulers for use in different environments. System resources which may include memory, input/output devices and file systems are thereafter optimally allocated for a selected set of applications and a particular environment within the data processing system by permitting a user to install a selected one of the multiple schedulers which directly controls allocation of processor time, thereby indirectly allocating system resources. The standardized interface within the operating system kernel is preferably provided utilizing a kernel extension mechanism and installation of a selected one of the multiple schedulers may occur automatically, in response to system initialization, or may be selectively achieved during operation of the data processing system.

Abstract: A priority preemptive, time distribution operating system operating in accordance with the method of the present invention provides enhanced efficiency in operation of a data processing system having a central processing unit, a computer memory and an auxiliary memory. The operating system manages the central processing unit, the computer memory and the auxiliary memory where a plurality of processes are presented for execution on the central processing unit by: ordering the processes for execution; allocating a predetermined time slice for execution of a process from the ordering; executing a first current process in the ordering on the central processing unit for the predetermined time slice; responsive to occurrence of a storage access operation during execution of the first current process, allocating a supplemental time slice to the current process for execution; and continuing execution of the current process for the supplemental time slice.

Abstract: Programs written for an action oriented graphic user interface are transferred to an object oriented graphic user interface. Upon installation of a program the data file types cognizable to the program are recovered from an association table for the program. A template is generated for each data file type and an icon is set on each template. Each template is then placed into an associated templates folder.

Abstract: A controller in a personal computer operating system continuously monitors for signals indicating continued powering of an attached keyboard, mouse or other pointing device. Loss of this signal is caused by the accidental or intentional loss of power to the external device or by physically disconnecting the device. Absence of the signal causes the setting of a timeout bit in the device status byte. When the attached device signals that it has successfully become re-powered, the initialization program routine of the operating system is recalled so as to return the device to on-line status without requiring a restart of the entire operating system.

Abstract: An adaptation of a computer operating system manages storage of EA (extended attribute) data in association with object names, the latter representing paths in direct access storage devices (e.g. directories and sub-directories), and data files stored in such paths. EA data stored in association with a data file name can be accessed either jointly with or separate from the respective data file. EA data comprises one or more variable length sets of bytes stored in disk drive sectors assigned by the operating system. The location of each set is determinable by means of an EA handle that is stored in a path table containing the respective object name. Function calls from application programs to the operating system use either a file name or EA handle to access EA data. Function calls specifying only an EA handle allow EA information to be stored, modified or read without specific association to or linkage with file data.

Abstract: An apparatus for loading BIOS stored on a direct access storage device in a personal computer system, the system comprising direct access storage device, and a processor card removably mounted to a planar board. The processor card comprises a system processor and ROM memory, while the planar board includes a main memory. A master boot record is stored on the direct access storage device. The master boot record contains a data segment and an executable code segment, the data segment representing the hardware configuration of the personal computer system. A first portion of BIOS included in the ROM memory initializes the system and causes loading of the master boot record into main memory. This first portion of BIOS further compares the hardware configuration data of the master boot record with the hardware configuration data in the ROM memory to verify compatibility with the system processor.

Abstract: Lazy Write disk cache systems are often utilized in disk cache designs. In such systems, data to be written to the disk storage system is temporarily placed in cache memory for a preselected period of time until an actual update of the disk occurs. By deferring disk write operations input/output performance efficiency is enhanced. However, in sector-based disk storage systems in which data may only be read from or written to a disk in predetermined fixed amounts an attempted update of data often requires a read of data from the disk storage system to ensure that existing data is not written over during an update. The method and system of the present invention avoids this problem by maintaining a status table for each block of cache memory which includes an identification of each byte within each block of cache memory which will be updated.

Abstract: An apparatus for scanning bar code data recorded on a target includes a source emitting a beam of radiation, and optics for deflecting the beam of radiation along an axis normal to the beam. The apparatus further includes an electronic shutter element defining a plurality of adjacent regions, each region independently capable of assuming a substantially transparent state, and, digital logic, for causing the adjacent regions of the shutter element to assume substantially transparent states in a sequential, directional manner along the axis to affect directional transmission of less than all of the deflected beam onto the target. The apparatus further includes a detector for sensing the presence of radiation reflected from the target, and, optics for converting the radiation reflected from the target into a beam and for focussing the beam onto the detector.

Abstract: A graphical user interface for a data processing system includes a method of generating a popup menu of actions allowed on an object represented in the graphical user interface. The method includes the steps of interrogating extended attributes for an object and each elder object to the object. Interrogation is for default actions and suppression markers. With each interrogation step the method adds actions linked to the object or to an elder object by another application and removes actions identified by suppression markers by another application from an interim list. After interrogation of the layers for modifications from other applications, the method provides for determining if any user defined actions and suppression markers are present for the object. If yes, the user defined actions are added to the interim list and actions matched by the suppression markers are removed from the interim list. A popup menu is then generated from the interim list.

Abstract: A termination circuit having a large margin which prevents the occurrence of a reflected wave due to a noise at the far end of a transmission line, thereby reducing the power consumption in the termination impedance. The termination circuit is constructed such that a first transistor is connected to a first potential and a second transistor is connected to a second potential which constitute the output stage of the termination circuit. The transistors are driven by first and second inverters having different input/output characteristics, respectively, thereby increasing the operation margin of the termination circuit. Particularly, if the second potential is assumed to be lower than the first potential, the second inverter driving the second transistor has such input/output characteristics that it outputs an output voltage which turns off the second transistor before the first inverter turns on the first transistor as the input voltage increases.

Abstract: A data processing system, such as a personal computer, contains bootable DOS programs that are stored in a ROM as an alternate file system in which the files are stored in packed format. When the system is powered on, the programs are rapidly booted up or loaded from ROM into RAM and executed to "instantly" (as it appears to the user) place the system in operation.

Abstract: A data processing system is operable in a multitasking mode to include at least one process having a plurality of threads. Exception management is done on a per thread basis, as opposed to a per process basis. Further, when a process termination exception occurs, each thread is accessed to execute any process termination exception handler associated with the thread.

Abstract: A computer system includes a keyboard which includes cooperatively operating therewith a keyboard device driver to enable the keyboard to interface with an operating system and applications program running within the computer system. Further types of input devices, such as handprint terminals, light pens, etc., can be employed in place of a keyboard to interact with the operating system and application programs running within the computer system. A keyboard device driver emulator is provided which transforms input data from the alternate input device so as to have said data appear to be keyboard generated data which is then transmitted to the operating system and applications running within the computer system. The invention also relates to a method of operating a computer system with an input device which is not a keyboard, but operating the system as if the input device were a keyboard by transforming the data from the input device to make it appear to be keyboard generated data.

Abstract: In a multitasking data processing system, I/O requests to a disk drive are staged in holding queues from which they are transferred to a service queue. Requests in the latter queue are directly serviced on a FIFO basis by a device driver module running on the system. The system maintains a set of holding queues and an associated service queue separately for each physical drive in the system. Holding queues in each set are prioritized in accordance with base priorities of tasks, and I/O requests to disk drives are entered into associated holding queues having priorities corresponding to those of task threads for which such requests are originated. Prioritization of the holding queues, and a starvation advancement process performed to advance "oldest" enqueued requests to higher priority holding queues, causes the requests to be presented to the disk drive in a sequence based in part on respective task priorities and in part on "fairness" servicing of "service starved" requests.