Microcontroller with in-circuit user programmable microcode
First Claim
Patent Images
1. A keyboard controller for use in a computer system to control and manipulate data passing between a keyboard and a computer system, the keyboard controller comprising:
- a central processing unit for controlling and manipulating data passing between the keyboard and the computer system in accordance with a control program;
a program random access memory (program RAM) for receiving and storing the control program;
a bus for transferring data, with the bus being coupled to the keyboard, the central processing unit, and the computer system; and
a program access enable unit coupled to the bus, the computer system and the program RAM, with the program access enable unit being selectively set in a first state or a second state so that when the program access enable unit is in the first state the control program is transferred directly from the computer system to the program RAM, without being transferred over the bus, via the program access enable unit, and when the program access enable unit is in the second state data is transferred between the bus and the program RAM via the program access enable unit.
0 Assignments
0 Petitions
Accused Products
Abstract
An architecture is described for a single chip microcontroller wherein the microcode stored in the microcontroller'"'"'s program memory may be easily modified without refabrication or removal of the microcontroller from its target environment. This is made possible by the utilization of a RAM based architecture for program memory instead of the traditional ROM based architecture.
30 Citations
10 Claims
-
1. A keyboard controller for use in a computer system to control and manipulate data passing between a keyboard and a computer system, the keyboard controller comprising:
-
a central processing unit for controlling and manipulating data passing between the keyboard and the computer system in accordance with a control program; a program random access memory (program RAM) for receiving and storing the control program; a bus for transferring data, with the bus being coupled to the keyboard, the central processing unit, and the computer system; and a program access enable unit coupled to the bus, the computer system and the program RAM, with the program access enable unit being selectively set in a first state or a second state so that when the program access enable unit is in the first state the control program is transferred directly from the computer system to the program RAM, without being transferred over the bus, via the program access enable unit, and when the program access enable unit is in the second state data is transferred between the bus and the program RAM via the program access enable unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method of performing keyboard control for the control and manipulation of data passing between a keyboard and a computer system, the method comprising the steps of:
-
setting a program access enable unit to a first state; transferring a control program directly from the computer system to a program random access memory (program RAM) via the program access enable unit while the program access enable unit is in the first state; setting the program access enable unit to a second state after the control program has been transferred to the program RAM; and controlling and manipulating data transferred over a bus between the keyboard and the computer system by a central processing unit which is coupled to the bus, with the central processing unit operating according to the control program in the program RAM.
-
Specification