Instruction set architecture

An instruction set architecture is an abstract model of a computer. It is referred to as architecture or computer architecture. A realization of an ISA, such as a central processing unit, is called an implementation. In general, an ISA defines the supported data types, the registers, the hardware support for managing main memory fundamental features, the input/output model of a family of implementations of the ISA. An ISA specifies the behavior of machine code running on implementations of that ISA in a fashion that does not depend on the characteristics of that implementation, providing binary compatibility between implementations; this enables multiple implementations of an ISA that differ in performance, physical size, monetary cost, but that are capable of running the same machine code, so that a lower-performance, lower-cost machine can be replaced with a higher-cost, higher-performance machine without having to replace software. It enables the evolution of the microarchitectures of the implementations of that ISA, so that a newer, higher-performance implementation of an ISA can run software that runs on previous generations of implementations.

If an operating system maintains a standard and compatible application binary interface for a particular ISA, machine code for that ISA and operating system will run on future implementations of that ISA and newer versions of that operating system. However, if an ISA supports running multiple operating systems, it does not guarantee that machine code for one operating system will run on another operating system, unless the first operating system supports running machine code built for the other operating system. An ISA can be extended by adding instructions or other capabilities, or adding support for larger addresses and data values. Machine code using those extensions will only run on implementations; the binary compatibility that they provide make ISAs one of the most fundamental abstractions in computing. An instruction set architecture is distinguished from a microarchitecture, the set of processor design techniques used, in a particular processor, to implement the instruction set. Processors with different microarchitectures can share a common instruction set.

For example, the Intel Pentium and the Advanced Micro Devices Athlon implement nearly identical versions of the x86 instruction set, but have radically different internal designs. The concept of an architecture, distinct from the design of a specific machine, was developed by Fred Brooks at IBM during the design phase of System/360. Prior to NPL, the company's computer designers had been free to honor cost objectives not only by selecting technologies but by fashioning functional and architectural refinements; the SPREAD compatibility objective, in contrast, postulated a single architecture for a series of five processors spanning a wide range of cost and performance. None of the five engineering design teams could count on being able to bring about adjustments in architectural specifications as a way of easing difficulties in achieving cost and performance objectives; some virtual machines that support bytecode as their ISA such as Smalltalk, the Java virtual machine, Microsoft's Common Language Runtime, implement this by translating the bytecode for used code paths into native machine code.

In addition, these virtual machines execute less used code paths by interpretation. Transmeta implemented the x86 instruction set atop VLIW processors in this fashion. An ISA may be classified in a number of different ways. A common classification is by architectural complexity. A complex instruction set computer has many specialized instructions, some of which may only be used in practical programs. A reduced instruction set computer simplifies the processor by efficiently implementing only the instructions that are used in programs, while the less common operations are implemented as subroutines, having their resulting additional processor execution time offset by infrequent use. Other types include long instruction word architectures, the related long instruction word and explicitly parallel instruction computing architectures; these architectures seek to exploit instruction-level parallelism with less hardware than RISC and CISC by making the compiler responsible for instruction issue and scheduling.

Architectures with less complexity have been studied, such as the minimal instruction set computer and one instruction set computer. These have not been commercialized. Machine language is built up from discrete instructions. On the processing architecture, a given instruction may specify: particular registers particular memory locations particular addressing modes More complex operations are built up by combining these simple instructions, which are executed sequentially, or as otherwise directed by control flow instructions. Examples of operations common to many instruction sets include: Set a register to a fixed constant value. Copy data from a memory location to a register, or vice versa. Used to store the contents of a register, the result of a computation, or to retrieve stored data to perform a computation on it later. Called load and store operations. Read and write data from hardware devices

Seminary Ridge

Seminary Ridge is a dendritic ridge, an area of Battle of Gettysburg engagements in July 1863 during the American Civil War, of military installations during World War II. Seminary Ridge is a northern portion of the drainage divide between the Marsh Creek Watershed on the west and the Rock Creek Watershed. At the south end of Oak Ridge, the north-south McPherson and Seminary ridges bifurcate southward at the triple watershed point of Willoughby and Pitzer runs with a Rock Creek eastward tributary. From the triple point, Seminary Ridge extends southward to an area with eastward drainage into the Rock Cr tributary, with the borough of Gettysburg, with the TBD. Farther south into the Gettysburg National Park, Seminary Ridge continues as far as a branch of Pitzer Run, which divides the ridgeline, around which the drainage divide curves to the east; the ridgeline continues south of the branch. Between the Millerstown and Emmitsburg road crossings, the west side of the ridgeline is an elevated area about 1 mile wide along the Emmitsburg Road.

Along this east side of this elevated area, the ridgeline is Warfield Ridge, the southernmost portion of Seminary Ridge near the south end of the Gettysburg Battlefield. South of the tip of Seminary/Warfield Ridge tip, the Marsh/Rock creeks' drainage divide continues about 4 miles to near the Mason–Dixon line at their confluence to form the Monocacy River; the portion of Seminary Ridge on the western side of Gettysburg, Pennsylvania includes the railroad cut behind houses north of Buford Avenue and the historic Gettysburg Armory. Extending south are Schultz Woods, Spangler Woods, Berdan Woods, the McMillan Woods Youth Campground, Pitzer Woods, Biesecker's Woods, the 1895 Longstreet Tower, which provides an observation platform for the "southern end" of Seminary Ridge; the Eisenhower National Historic Site on the west of the ridge is visible from the tower. Seminary Ridge Avenue and the sections of West Confederate Avenue extend along the landform's ridgeline and provide access to numerous battle monuments on the ridge, including the prominent Virginia Monument.

Seminary Ridge is crossed by Springs avenues, as well as West Middle Street. South Seminary Ridge is a Gettysburg Battlefield landform south of an east-west branch of Pitzer Run, which separates South Seminary Ridge from a separate landform to the north on the west of Gettysburg with the Lutheran Theological Seminary at Gettysburg. South of the Pitzer Run branch, the ridgeline of South Seminary Ridge extends from Pitzer Woods, across the Millerstown Road, past the Longstreet Tower to the Emmitsburg Road and on to the southernmost state memorial on the battlefield, just west of the right flank marker for the Confederate Line. Warfield Ridge is a portion of South Seminary Ridge southward to the Alabama Memorial, the ridge landform continues southward out of the Gettysburg National Park to where Ridge Road is on the crest; the 1761 Samuel Gettys tavern was built near the ridge at the crossroads east of Stevens Creek, it preceded both the c. 1812 construction of the Chambersburg Pike across the ridge and the nearby "Gettysburg Theological Seminary" being established on the ridge on August 1, 1826.

In 1832, Old Dorm was built, Pennsylvania College was started on the east side of the ridge. On the ridge along the Chambersburg Pike, the Thaddeus Stevens building near the seminary was built in 1834. At the time of the battle, the section of the ridge at the extension of West Middle St was known as "Haupt's Hill". Seminary Ridge was the site of Battle of Gettysburg fighting on July 1, 1863, as well as a Pitzer Woods engagement on July 2. Robert E. Lee established his headquarters on the ridge just north of the Chambersburg pike, the ridge served as the Confederate line of battle for July 2 & 3 attacks against Union Army positions on Cemetery Ridge. On July 3, 500 men in George Pickett's division were killed/wounded on Seminary Ridge from the Federal artillery counterfire prior to Pickett's Charge; the last hospital patient of the seminary's Old Dorm left on September 16, 1863. Longstreet Tower was built on the ridge by the War Department in 1895. West Confederate Avenue was built at the turn of the 20th century for Seminary Ridge tourism, while Sharpshooters Avenue was extended from W Confederate Avenue in 1917 for access to a Pitzer Woods monument.

In 1918, various military camp sites were located in the "Field of Pickett's Charge" between the Seminary and Cemetery ridges. The North Carolina Monument was placed on the ridge in 1929; the Civilian Conservation Corps built the 1938 Civil War veteran's camp for the 75th Anniversary of the Battle of Gettysburg and performed Gettysburg Battlefield landscaping through 1941. Construction had begun c. November 1933 for Gettysburg CCC camp "NP-2", which opened May 26, 1934 on Seminary Ridge and closed in 1941. Renamed from "MP-2", camp NP-2 was in McMillan Woods, while a different CCC camp was in Pitzer Woods from 1935 until closing in April 1937; the Pitzer's Woods camp was for reforestation and a 1933 "cyclone" blew all 45 tents down. The "Gettysburg Company 1355, C. C. C." Celebrated their 8th anniversary in 1941. During 1943-4, Camp Sharpe at the former P

Robert W. MacDonald

Robert W. MacDonald is an American insurance entrepreneur, business consultant and author of business books. MacDonald began his career as a door-to-door salesman and became a CEO of three major insurance companies, he was president of ITT Life Insurance Company, was a founder and CEO of Life USA. He sold Life USA in 1999 to Allianz SE for $540 million and became CEO of Allianz Life of North America before retiring in 2002. With a 40+-year career in the financial services industry, MacDonald has been cited in the media as a business maverick, who has “earned a reputation as a business contrarian who rewrote the rules of business and corporate culture.” He was twice voted Entrepreneur of the Year in Minnesota. MacDonald has since 2002 headed CTW Consulting, LLC, a vehicle he used to offer his experience and unique approach to management and corporate culture development. Robert W. "Bob" MacDonald was born in the son of middle-class parents. His father had been a mortician before World War II, but became an X-ray technician after developing an allergic reaction to embalming chemicals.

His mother worked in the medical field as a nurse and medical secretary. The MacDonald family moved West in 1946, first to Arizona and to California where MacDonald spent most of his formative years. A rebellious and mischievous youth, MacDonald’s parents attempted to shape up the youth by sending him to the structured St. John's Military Academy and to Loyola High School, a Jesuit college preparatory school for young men in hopes of reforming his contrarian lifestyle, but his disrespect for traditional rules continued. Although he grew up in a family of health care specialists, he was hired as a 17-year-old high school junior by Coast Federal Savings & Loan of Los Angeles to deliver patriotic speeches to rotary clubs, veterans’ groups and other organizations, he was paid $50 $1 for every audience member. He earned hundreds of dollars each week. MacDonald’s contrarian lifestyle first came to the notice of national media when he bluffed his way into the 1960 Democratic National Convention headquarters of the Democratic National Committee, at the Biltmore Hotel in Los Angeles.

The 17-year-old MacDonald spent a week mingling with delegates, rubbing shoulders with John F. Kennedy, Lyndon Johnson, Bobby Kennedy. A suspicious newspaper reporter discovered MacDonald’s fraud; the now defunct Los Angeles Herald-Examiner profiled MacDonald the following day as “The Delegate Who Isn’t Spins a Yarn.”MacDonald pulled a similar prank during the 1960 presidential campaign when John F. Kennedy was the featured speaker at a rally at the Shrine Auditorium in Los Angeles. MacDonald faked his way onto the stage where the youthful prankster was seated a few feet from JFK. In 1965, MacDonald became a neophyte “knock-on-the-door” insurance agent for New England Mutual Life (later absorbed by Metropolitan Life. MacDonald built sales agency in Southern California for Jefferson-Pilot, served as director of marketing support for State Mutual of America and was chief marketing officer, chief operating officer president and CEO of Minneapolis-based ITT Life, owned by The Hartford; as president and CEO of ITT Life Insurance Corp. he became “one of the best known, most influential and controversial leaders in the life insurance industry, flamboyant in an industry in which flamboyance is rare and unrewarded.”

The New York Times described MacDonald as “an innovator and unrepentant bad boy in the go-along-to-get-along insurance. In the early 1980s, as president of ITT Life Insurance, he launched a public campaign against his industry's most popular family of policies -- whole life. ”He had the bad taste to say what everybody knew: Whole life insurance had ceased to be a good buy” and further charged the insurance industry with being “ossified, petrified and inbred.” In response, he was vilified by his peers. The pundits notwithstanding, his “Your Whole Life is a Mistake” advertising and publicity campaign was a major success. In the late 1980s, having led an expansion of the company, MacDonald tried to buy ITT and instead, was fired, he formed a new life insurance company, Life USA in Minneapolis-St. Paul The new insurance company offered independent agents who sell its policies an ownership stake in the company, and encouraged agents to become “capitalists rather than captives”As a founder, chairman and CEO, MacDonald led Life USA into a profitable, publicly traded company with sales exceeding $1 billion, assets of more than $6 billion and more than 80,000 agents contracted to represent the company.

In 1999, he sold the company to Munich, Germany-based financial services giant Allianz in a deal valued at $540 million. Life USA was merged with the larger Allianz Life of North America. In an unusual corporate move, MacDonald was asked to continue on as CEO of the merged companies. Under his direction, according to the Minneapolis/St. Paul Business Journal, Allianz Life became a star performer in the Allianz worldwide group. In 2006, he was lured out of retirement to kick-start and serve as the chief executive of Allianz Income Management Services, a new company formed by Allianz to respond to retirement income needs of retiring baby boomers, he resigned from the position in 2007. MacDonald is the author of several business books, his latest work, Old MacDonald's Ethical Leadership Farm: Growing New Leaders for New Times. His earlier works include Beat The System: 11 Secrets to Building an Entrepreneurial Culture in a Bureaucratic World, (John Wi