Locating Specialized Controller Microcode on Device Card
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
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.