Video Output On The Machines
Reading a value from, or writing any value to, certain memory addresses controlled so called "soft switches". The value read or written does not matter, what counts is the access itself. This allowed the user to do many different things including displaying the graphics screen (any type) without erasing it, displaying the text screen, clearing the last key pressed, or accessing different memory banks. For example, one could switch from mixed graphics and text to an all-graphics display by accessing location 0xC052 (49234). Then, to go back to mixed graphics and text, one would access 0xC053 (49235).
Read more about this topic: Apple II Graphics
Famous quotes containing the words video, output and/or machines:
“These people figured video was the Lord’s preferred means of communicating, the screen itself a kind of perpetually burning bush. “He’s in the de-tails,” Sublett had said once. “You gotta watch for Him close.””
—William Gibson (b. 1948)
“Lizzie Borden took an axe
And gave her mother forty whacks;
When she saw what she had done,
She gave her father forty-one.”
—Anonymous. Late 19th century ballad.
The quatrain refers to the famous case of Lizzie Borden, tried for the murder of her father and stepmother on Aug. 4, 1892, in Fall River, Massachusetts. Though she was found innocent, there were many who contested the verdict, occasioning a prodigious output of articles and books, including, most recently, Frank Spiering’s Lizzie (1985)
“In Hell all the messages you ever left on answering machines will be played back to you.”
—Judy Horacek (b. 1961)