Browse Prior Art Database

Program Controlled I/O Address Assignment

IP.com Disclosure Number: IPCOM000079279D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Rosenberg, LJ: AUTHOR

Abstract

Dynamic address assignment to control units is accomplished by the following structure. I/O devices are attached to an I/O controller 10 by device adapters 1, 2, and 3 over a device/controller interface 12. Each device adapter is assigned a reset address. Each device adapter may also accept a program address supplied from a central processor over the I/O interface to the controller. An I/O OP line and an ENABLE PA line are used to select an adapter. The I/O OP line connects to the adapters in parallel and is not redriven from adapter-to-adapter. The ENABLE PA is generated at each adapter, and is connected to the next adapter down the line. The ENABLE PA line is not propagated to device adapters farther down the line, if the adapter has no address assignment other than the reset address.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 61% of the total text.

Page 1 of 2

Program Controlled I/O Address Assignment

Dynamic address assignment to control units is accomplished by the following structure. I/O devices are attached to an I/O controller 10 by device adapters 1, 2, and 3 over a device/controller interface 12. Each device adapter is assigned a reset address. Each device adapter may also accept a program address supplied from a central processor over the I/O interface to the controller. An I/O OP line and an ENABLE PA line are used to select an adapter. The I/O OP line connects to the adapters in parallel and is not redriven from adapter-to- adapter. The ENABLE PA is generated at each adapter, and is connected to the next adapter down the line. The ENABLE PA line is not propagated to device adapters farther down the line, if the adapter has no address assignment other than the reset address. If the device adapter has an address assignment preset (because the program feature is not incorporated into the device adapter) or if the device adapter has already been assigned a program address, the ENABLE PA line is propagated to the next device.

The I/O interface addresses and selects an I/O controller by placing a reset address on the interface 12 and energizing the I/O OP line. A device whose working address is its reset address responds to the I/O OP line. The I/O interface then supplies the I/O-controller with the program address, which is transferred by the controller to the device. The device sets the program address into an a...