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'''Mode X''' is an undocumented video graphics display mode of the [[International Business Machines|IBM]] [[VGA]] graphics hardware that was popularized by [[Michael Abrash]], first published in July 1991 in [[Dr. Dobb's Journal of Computer Calisthenics & Orthodontia|Dr. Dobb's Journal]], republished in chapters 47-49 of Abrash's ''Black Book of Graphics Programming'', which is now freely available online in PDF. [http://www.gamedev.net/reference/articles/article1698.asp]
'''Oscar L. Chapman''' was the [[United States Secretary of the Interior]] during the
last three years of the [[Harry S. Truman|Truman]] administration.
Mode X involves tweaking IBM's standard [[Mode 13h]] 256 colour graphics mode such that all the video memory is made available to the programmer in a [[planar]] fashion, at the expense of extra complexity in writing to video memory. For many programmers, this expense is well worth the effort as the extra video memory available makes it possible to produce high quality [[2D]] games or [[Demo (computer programming)|demo]]s, things that this mode was primarily used for.
Chapman was born on October 22, 1896 in [[Omega, Virginia]]. He served in the United States Navy Medical Corpos from 1918 to 1920. He attended the [[University of Denver]] and the [[University of New Mexico]] and earned his LL.D. at [[Westminister Law School of Denver]].
The main uses of the extra memory are:
He was the manager of [[Edward P. Costigan]]'s senate campaign in 1930, and the [[Alva B. Adams]] campaign in 1932. After [[Franklin Delano Roosevelt|Franklin D. Roosevelt]]'s election in 1932, he was appointed as an assistant secretary in the interior department.
*Higher resolutions: up to 360×480 in 256 colours is possible
In 1939, Chapman was an early victim of the [[House Committee on Un-American Activities]], as then chairman [[Martin Dies Jr.]] published a list of government employess who were members of a communist controlled organization (Chapman was considered a member because there was a record that he had contributed two dollars to the [[American League for Peace and Democracy]] which was raising money for the loyalists during the [[Spanish Civil War]].
*[[Double Buffering]] for flicker free animation
*Hardware smooth scrolling
At 1944 [[Democratic National Convention]] in Chicago, he impressed Truman by sticking to his early agreement to support the current vice president [[Henry A. Wallace]]. He was promoted to under secretary by [[Harry S. Truman]] in 1946. He worked to promote Truman in the 1948 election, and in late 1949 was promoted again to secretary of the interior, replacing [[Julius A. Krug]] who had not supported Truman's campaign. Chapman worked closely with Truman, being one of his most liberal advisors. Chapman was one of those (along with [[Clark Clifford]]) who supported Truman's recognition of the state of [[Israel]] in May of 1948, over the objections of the State Department.
*Graphics store in 'off-screen' [[VRAM]] can quickly be moved around in VRAM using the VGA latches
*Planar mode allows up to 4 pixels to be modified in one byte write operation, which is ideal for solid filling of objects such as polygons, rectangles, lines, etc.
In 1951, Chapman denied a government loan to an aluminum company being run by [[Lea M. Harvey]] because of a scandal that Harvey had sold artillery shells to the Navy during [[World War II]] that were dangerously out of specification.
*Screen splitting, where one part of the display is taken from one area of memory and the other from a different area which is ideal for status displays in games utilising smooth hardware scrolling
After the end of the Truman administration in 1953, he practiced law in the firm of Chapman Duff and Paul.
He died on February 8, 1978.
{{USSecInterior}}
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