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Locating Specialized Controller Microcode on Device Card

IP.com Disclosure Number: IPCOM000045424D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Canova, FJ: AUTHOR [+4]

Abstract

A technique is described which enables additional and different kinds of I/O devices to be connected to an I/O controller card without having to modify the microcode previously designed for use on the controller card. This is accomplished by making the original controller microcode as generic as is necessary to keep out any device eccentricities. A small read-only storage (ROS) module is then located on each device adapter card for holding the specialized microcode which is peculiar to the I/O device connected to such adapter card. This specialized microcode is transferred at power-on time to a patch area P in a random-access memory (RAM) located on the I/O controller card.

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Locating Specialized Controller Microcode on Device Card

A technique is described which enables additional and different kinds of I/O devices to be connected to an I/O controller card without having to modify the microcode previously designed for use on the controller card. This is accomplished by making the original controller microcode as generic as is necessary to keep out any device eccentricities. A small read-only storage (ROS) module is then located on each device adapter card for holding the specialized microcode which is peculiar to the I/O device connected to such adapter card. This specialized microcode is transferred at power-on time to a patch area P in a random-access memory (RAM) located on the I/O controller card. After such transfer, the specialized microcode is used in combination with the generic microcode originally located on the controller card to control the various data transfer and other operations normally performed by the controller card.

As indicated by the drawing, this technique is particularly useful for the case where additional storage cards are to be coupled to a host processor by way of an I/O controller card. In this case, the adapter circuits are located on the same physical card as is the basic storage mechanism, and the specialized microcode is accommodated merely by adding a small ROS module to the card.

In a typical case, the generic controller microcode is located in an ROS unit on the controller card. At power-on time, t...