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System 360/370 Select Out/In Bypass Function With Driver and Receiver in One Chip

IP.com Disclosure Number: IPCOM000034823D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 5 page(s) / 80K

Publishing Venue

IBM

Related People

Larson, TR: AUTHOR [+2]

Abstract

An Integrated Select Out Bypass (ISOB) chip is disclosed that performs the Select Out and Select In control for a single IBM System 360 and System 370 I/O Interface. The Control Unit attached to the System 360/370 Channel Interface uses the Select Out signal to detect the start of a selection sequence from the Channel. Unlike the other interface lines, Select Out is not only received by each Control Unit but passes through logic and is (Image Omitted) re-driven to the next Control Unit attached to the Channel. The ISOB function provides an electrical bypass for the Select Out/Select In signal when the Control Unit is powered off.

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System 360/370 Select Out/In Bypass Function With Driver and Receiver in One Chip

An Integrated Select Out Bypass (ISOB) chip is disclosed that performs the Select Out and Select In control for a single IBM System 360 and System 370 I/O Interface. The Control Unit attached to the System 360/370 Channel Interface uses the Select Out signal to detect the start of a selection sequence from the Channel. Unlike the other interface lines, Select Out is not only received by each Control Unit but passes through logic and is

(Image Omitted)

re-driven to the next Control Unit attached to the Channel. The ISOB function provides an electrical bypass for the Select Out/Select In signal when the Control Unit is powered off. Besides the Select Out Bypass function, the ISOB design contains the Driver and Receiver used when the Control Unit is powered up to receive and re-drive the Select Out signal to the next Control Unit. Below is a detailed definition of each input and output terminal for the chip illustrated in Figs. 1 and 2. +Power Status Line "Power Status Line" is supplied by the Control Unit to signal that +Power Status Line "Power Status Line" is supplied by the Control Unit to signal that the Power On/Off Sequence is to be performed. The Power Status Line must remain low while the power supply line to the ISOB module is rising to +5 volts during power on.

The "Power Status Line" is the primary input control line to the module. When the bypass "relay A" is to be open, this line and "On Line" must both be high. When this line is low, the "Relay A" will be closed. + On Line This line provides the same function as the "Power Status Line". "Dropping" this line to "zero" will bypass the select out/select in line. This line is not required to be used for the module to function. Because of this there is an internal pull-up on this line. If the line is unused, no external connection is required. + Select Out Incoming The Select Out signal received at the Control Unit from the Channel or another upstream Control Unit is called "Select Out Incoming". This is the signal which is received by the Control Unit or electrically bypassed to the next Control Unit. Propagate Sel Out This input signals that the Control Unit selection hardware has determined that Select Out should be propagated to the next Control Unit. Note that this line is low active. -Tri-State TTL Outputs This input is used during testing to put all TTL outputs from the module in a high impedance state. It also allows the setting of the RAS output for test. This is a low active line. This TTL input has a built-in pull-up resistor to +5 volts. This means that if this line is not used, no connection is required at the input of the module. -RAS Reset When this line is pulsed low, the RAS output line, "Driver Short", is reset. +Terminator This output is required to connect the external resistor to the Select Out receiver. This resistor in combination with the internal module resistance of t...