US 5,673,418 AGranted

Method and apparatus for emulating the operations of an emulated system terminal driver on a host system

AssigneeBull HN Information Systems Inc.

InventorsJames W. Stonier, Michael E. Tessier

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Abstract

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a network terminal driver (NTD) component operating in the host memory. Configuration command means are provided for initially configuring a host terminal to operate in a plurality of asynchronous driver (ATD) modes implemented by the NTD component. When a terminal has been configured by a user to run applications written for the ATD driver, it sets a mode indication which causes the NTD component to respond to user applications as an ATD driver and determine if each ATD request can be carried out with functionality included within the NTD component. If the request can be carrier out, the NTD component translates ATD device specific information contained in each request into NTD device specific information which invokes the required functionality at the appropriate time so that the request can be processed by the NTD component. At the completion of each such request, the NTD component utilizing information contained in the original request updates the return status information to that of the ATD driver. This arrangement provides ATD applications access to NTD controlled host terminals without having to port ATD software or have users modify their existing applications.

Claims19

Dependent claims

A method for utilizing a first terminal driver (NTD) component having a number of different operational modes within a host system to accommodate the servicing of user applications designed to use a second driver (ATD) component, the host system having a memory and a hardware platform including a number of terminals used to enter commands for running user applications and for viewing results generated during running user applications, a host input/output services component operatively connected to different ones of the number of terminals for executing host system instructions of user applications, the second driver component having a family of operational modes defined by device specific information included in an input/output request block (IORB) associated with each request issued by a user application, the NTD component being operatively coupled to the input/output services component, the host system further including operating system facilities for providing services for host programs and for initially configuring each of number of terminals which is to utilize the family of second driver operational modes and the NTD component, the method comprising the steps of:

generating a response to an initial monitor call of a user application for determining which driver component is servicing one of the number of terminals being used to run the user application, the response indicating that the second driver component is servicing the terminal when the NTD component has determined that the terminal was previously configured to use the family of second driver operational modes;
translating second driver device specific information in the IORB of each executable request into NTD device specific information defining equivalent ones of the number of different operational modes to be used for executing the request by the NTD component operating in an second driver mode of operation which determines if a request is executable by the NTD component operating in an equivalent second driver mode of operation;
and,
mapping status information resulting from each executed request into the same format as status which would have been returned by the second driver component enabling the application to run unchanged in the host system.

1 more element

A first driver (NTD) component having a number of different operational modes for use in a host system having a memory and a hardware platform including a number of terminals used to enter commands for running user applications and for viewing results generated during running user applications, a host input/output services component operatively connected to different ones of the number of terminals for executing host system instructions of user applications wherein at least one user application designed to use a second terminal driver (ATD) component, the second driver component having a family of operational modes defined by device specific information included in an input/output request block (IORB) associated with each request issued by a user application, the NTD component being operatively coupled to the input/output services component, the host system further including operating system facilities for providing services for host programs and for initially configuring each of number of terminals which is to utilize the family of second driver operational modes and the NTD component, the NTD component comprising:

an input section in response to a monitor call received from a user application for determining which driver software is servicing one of the number of terminals being used to run the user application, generating a response indicating that the second driver component is servicing the terminal when the terminal has been previously configured by a user to use the family of second driver operational modes;
a preprocessor operatively coupled to the input section for receiving each request issued by the user application being run by the configured terminal, the preprocessor including a mechanism for translating second driver device specific information in the request IORB into NTD device specific information defining equivalent ones of the different operational modes to be used for executing the request by the NTD component operating in an second driver mode of operation which determines if the request is executable by the NTD component;
and,
a post processor operatively coupled to the input/output services component for receiving status information resulting from each executed request, the post processor mapping the status information into the same format as status which would have been returned by the second driver component enabling the application to run unmodified in the host system.

1 more element

Dependencies are inferred from the claim text.