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Multiple PC/5250 Sessions Without Unique Code

IP.com Disclosure Number: IPCOM000061031D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hansen, BW: AUTHOR [+2]

Abstract

A method is provided for supporting multiple concurrent sessions using a single personal computer (PC) which is emulating a terminal, such as the IBM 5250, attached to a host system, such as the IBM S/36. During a twinax interrupt from the master card, all sessions are serviced. All session-unique data is contained in on-card RAM, and addressed by simply changing the DS (data segment) register. No session unique code is required. A suitable hardware interface is supplied for each session to connect to the host computer. This method relies on the following specific hardware features of the emulation adapter: The base I/O address of the card is controllable. This allows multiple cards to be installed without I/O contention. The station address of each session can be controlled by software. This is an ease-of-use feature.

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Multiple PC/5250 Sessions Without Unique Code

A method is provided for supporting multiple concurrent sessions using a single personal computer (PC) which is emulating a terminal, such as the IBM 5250, attached to a host system, such as the IBM S/36. During a twinax interrupt from the master card, all sessions are serviced. All session-unique data is contained in on-card RAM, and addressed by simply changing the DS (data segment) register. No session unique code is required. A suitable hardware interface is supplied for each session to connect to the host computer. This method relies on the following specific hardware features of the emulation adapter: The base I/O address of the card is controllable. This allows multiple cards to be installed without I/O contention. The station address of each session can be controlled by software. This is an ease-of-use feature. The base address of on-card RAM is controllable. This allows multiple cards to be installed without memory contention. .The interrupt request line of each card can be disabled (put in . high-impedance state) under software control. This allows multiple cards to be installed without interrupt request contention. Each Enhanced PC/5250 Emulation adapter has two Link-TC chips and two areas of RAM. Each set services one emulation session. the program architecture allows multiple cards to be installed in a single PC and used concurrently. The total number of sessions is limited to seven by the twinax addressing architecture. It is important to be very economical in the amount of code that is unique to each session. This method uses the s...