I did some searching for likely patents, I'll post them here for posterity.
(Of course it isn't in WDC's interests to make it easy to know which patents they might use to defend their business.)
The patent search sites are a bit weak on name searches: you don't always get all the results you'd expect.
See Bill Mensch's various patents:
http://www.patentstorm.us/inventors-pat ... 414/1.html
http://www.patentstorm.us/inventors-pat ... 887/1.html
http://www.patentstorm.us/inventors-pat ... 561/1.html
http://www.patentstorm.us/inventors-pat ... 477/1.html
see also Chuck Peddle etc etc
http://www.patentstorm.us/inventors-pat ... 563/1.html
Here's a non-exhaustive list in an arbitrary order. There's often some interesting design notes buried within.
6052792 Power management and program execution location management system for CMOS microcomputer
A monitor program stored in a ROM of a microcomputer chip of a computer is operated both to (1) save power by disabling all external buses, turning off power to a communication port, deselecting all external memory devices, and turning off a fast clock os... 04/18/2000
5737613 Method of operating microcomputer to minimize power dissipation while accessing slow memory
A method of operating a CMOS microcomputer to minimize power dissipation while accessing a plurality of memories including a first memory operable at a first frequency, a second memory operable at a lower second frequency, including operating the entire C... 04/07/1998
5511209 Programmable microcomputer oscillator circuitry with synchronized fast and slow clock output signal
A CMOS integrated circuit microcomputer is switchable under software control between high speed, high power operation and low speed, low power operation. The microcomputer includes asynchronous fast and slow clock oscillators. A synchronizing circuit coup... 04/23/1996
5438681 Topography for CMOS microcomputer
The topography of an 84 lead CMOS microcomputer chip includes first, second, third, and fourth consecutive edges, with chip control logic being located along the upper left edge. The chip includes six multiplexed peripheral I/O port buffer circuits, a dat... 08/01/1995
5212800 Method and apparatus for sensing trinary logic states in a microcomputer using bus holding circuits
A CMOS integrated circuit microcomputer system includes circuitry for sensing trinary logic states by using a tri-state driver circuit connected to both the input and output of a binary latch having only two states, both of which produce a high output imp... 05/18/1993
5123107 Topography of CMOS microcomputer integrated circuit chip including core processor and memory, priority, and I/O interface circuitry coupled thereto
The topography of a CMOS microcomputer chip includes first, second, third, and fourth consecutive edges, with chip control logic being located along the upper left edge. Five peripheral I/O port buffer circuits are located around the edge of the periphery... 06/16/1992
4876639 Method and circuitry for causing sixteen bit microprocessor to execute eight bit op codes to produce either internal sixteen bit operation or internal eight bit operation in accordance with an emulation bit
A sixteen bit microprocessor includes an emulation bit that is loaded into an instruction register with 8 bit op codes. If the emulation bit is a "1", the 16 bit microprocessor operates internally as a 6502 type eight bit microprocessor, thereby emulating...
4800487 Topography of integrated circuit including a microprocessor
The topography of a CMOS microprocessor chip includes address buffer circuitry along the bottom and lower left hand edges of the chip, data bus buffers disposed along the lower right hand edge of the chip, address register circuitry and an arithmetic logi... 01/24/1989
4739475 Topography for sixteen bit CMOS microprocessor with eight bit emulation and abort capability
The topography of a sixteen bit CMOS microprocessor chip including circuitry for enabling it to emulate, under software control, a prior art 6502 microprocessor includes an N-channel minterm logic section including 498 "vertical" diffused minterm lines ac... 04/19/1988
4652992 Topography of integrated circuit CMOS microprocessor chip
The topography of a CMOS microprocessor chip includes address buffer circuitry along the bottom and lower left hand edges of the chip, data bus buffers disposed along the lower right hand edge of the chip, address register circuitry and an arithmetic logi... 03/24/1987
3968478 Chip topography for MOS interface circuit
The chip architecture of an MOS peripheral interface adaptor chip includes data bus buffers arranged along one edge of the chip, peripheral interface buffers arranged along an opposite e
5097413 Abort circuitry for microprocessor
An abort circuit for a microprocessor includes a circuit receiving and latching an external abort signal to produce an internal abort signal, and circuitry responsive to the internal abort signal for preventing register transfer circuitry from responding ... 03/17/1992
4263650 Digital data processing system with interface adaptor having programmable, monitorable control register therein
A digital system including a plurality of metal-oxide-semiconductor (MOS) chip random access memories (RAM), read only memories (ROM) and peripheral interface adaptors coupled to a common bidirectional data bus which is coupled to and controlled by a micr... 04/21/1981
4218740 Interface adaptor architecture
A peripheral interface adaptor (PIA) circuit for data processing systems contains memory elements or control registers allowing modification under program control of the logical functions of the PIA. The peripheral interface adaptor includes a plurality of sys... 08/19/1980
4087855 Valid memory address enable system for a microprocessor system
A digital system includes a microprocessor coupled to a data bus and an address bus. A memory for storing data and instructions is connected to the data bus and the address bus. A peripheral device is connected to an interface adaptor. The interface adapt... 05/02/1978
4086627 Interrupt system for microprocessor system
A microprocessor system includes a microprocessor, a memory, and an interface adaptor all coupled to a data bus. The interface adaptor is coupled between the data bus and a peripheral device, such as a teleprinter. A first interrupt conductor is connected... 04/25/1978
4020472 Master slave registers for interface adaptor
An interface adaptor suitable for use in a microprocessor system includes an input register coupled to a bidirectional data bus of the microprocessor system. The interface adaptor includes a plurality of registers, including a control register and a data ... 04/26/1977
3991307 Integrated circuit microprocessor with parallel binary adder having on-the-fly correction to provide decimal results
Disclosed is an integrated circuit microprocessor with a parallel binary adder whose output can be corrected on-the-fly to provide decimal results. The correction is by logical gating which operates selectively and on-the-fly, that is, while the sum from ... 11/09/1976
Sorry it isn't terribly well formatted. There are several sites which will give you a PDF for each patent, once you have the patent number.