Browse Prior Art Database

Optional Insertion of Integrated Circuit Module on Multi-Protocol Communication Card

IP.com Disclosure Number: IPCOM000048491D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Frye, JL: AUTHOR [+2]

Abstract

Integrated circuit module 1 is a programmable HDLC/SDLC protocol controller providing high level and synchronous data link control in a communications adapter. Some applications of the communications adapter will require that the synchronous data link control (SDLC), binary synchronous communication protocol (BSC), and start/stop (SS) protocol be provided, while other applications will require BSC and SS only. Thus, the integrated circuit module 1 is an optional module depending on the specific application of the communications adapter. Problems are encountered with having optional integrated circuit modules because the signals that are being driven by that module cannot be guaranteed to be at any value whenever the integrated circuit chip is not present.

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Optional Insertion of Integrated Circuit Module on Multi-Protocol Communication Card

Integrated circuit module 1 is a programmable HDLC/SDLC protocol controller providing high level and synchronous data link control in a communications adapter. Some applications of the communications adapter will require that the synchronous data link control (SDLC), binary synchronous communication protocol (BSC), and start/stop (SS) protocol be provided, while other applications will require BSC and SS only. Thus, the integrated circuit module 1 is an optional module depending on the specific application of the communications adapter. Problems are encountered with having optional integrated circuit modules because the signals that are being driven by that module cannot be guaranteed to be at any value whenever the integrated circuit chip is not present. This problem becomes more acute because the active collector outputs generally cannot handle pull-down resistors. 0n outputs that can be inactive at a high level, a large pull-up resistor (22 K Omega) can be used, but for signals that are inactive low, some gating must be provided.

As shown in the figure, this is accomplished by using one of the general purpose outputs of the integrated circuit chip itself. A command must be issued to set this output to a low value in order for the other outputs of the chip to be enabled. This output is pulled up with a resistor 2 and goes into the input of an inverter 3. The inverter output goe...