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SAVE Function in the IBM 3270 Emulation Feature of the IBM Displaywriter

IP.com Disclosure Number: IPCOM000041614D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Clements, SF: AUTHOR [+3]

Abstract

A new function, SAVE, has been created for the IBM 3270 Data Stream Compatibility (DSC) feature of the IBM Displaywriter. This function saves the contents of the display screen and transfers it to a diskette. While the SAVE function is being performed, the host computer must not be permitted to update the screen. If the host were permitted to send data while the SAVE was being performed, it would be necessary to provide a duplicate screen buffer in order to preserve the screen data until the SAVE function was completed. Otherwise, the host could write over the screen while it was being saved. This additional memory and the additional coding it would require would be expensive.

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SAVE Function in the IBM 3270 Emulation Feature of the IBM Displaywriter

A new function, SAVE, has been created for the IBM 3270 Data Stream Compatibility (DSC) feature of the IBM Displaywriter. This function saves the contents of the display screen and transfers it to a diskette. While the SAVE function is being performed, the host computer must not be permitted to update the screen. If the host were permitted to send data while the SAVE was being performed, it would be necessary to provide a duplicate screen buffer in order to preserve the screen data until the SAVE function was completed. Otherwise, the host could write over the screen while it was being saved. This additional memory and the additional coding it would require would be expensive. The most appropriate solution to the problem would seem to be the definition of a new error code which would be returned to the host in the response that rejected its attempt to update the screen. However, this would require that all host programs that send data to the 3270 DSC would have to be modified to recognize this new error code and react appropriately. A simpler solution is to use an existing mechanism that accomplishes the same goal. The Local Print function has the same requirement of not permitting the host to update the screen while screen print is being performed. If the host sends a request while the Local Print function is active, it is rejected with a negative response whose error code tells the host it...