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59 lines
2.9 KiB
Plaintext
Executable File
59 lines
2.9 KiB
Plaintext
Executable File
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This file describes the functional characteristics of the Ann Arbor Display
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Controller. These terminals come in various screen sizes (16. x 32., 20. X 50,
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24. x 80., and 40. x 80.) and come as display controllers (sans monitor) or
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as an integrated display. Some models (rare) have winning features like
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Clear EOL, inverse video, blink, etc. but the most common variety don't
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have any of these features. The standard controller has a 24. x 80. screen.
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It can come with a serial (up to 9600 baud) interface or parallel (up
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to 1620 chars/sec or approximately 16K baud - cursor controls are faster).
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Characters are written on the screen at the cursor position in overwrite
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mode (i.e. what was there previously is deleted) - this includes space
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(ASCII 40), which is used for erasing due to the absense of Clear EOL, etc.
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Writing in the last column of a line (80. if the first column is 1) causes
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the cursor to be advanced to the first column of the next line. On the
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last line of the screen, this causes wraparound to the top line of the
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screen.
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There are 8 cursor control commands:
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Erase Screen (FF - 14): Takes about 1/30'th of a second, leaves the cursor
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at the top left corner of the screen (0,0).
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Carriage Return (CR 15): The usual, takes no time (just sets the cursor
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register).
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Linefeed (LF 12): The usual, timing simlar to CR. On the bottom
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line of the screen, it will wraparound to the same horizontal
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position on the top line of the screen, or it will cause scrolling
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depending on a switch on the controller (wraparound is the prefered
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mode of operation).
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Back Space (BS 10): Moves the cursor back one character position.
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In column 0, it moves the cursor back to column 79. (the last one)
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of the SAME line. Thus its behavior is not analogous to
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Cursor Right (which proceeds onto the next line).
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Cursor Home (VT 13): Move the cursor to 0,0 (top left corner)
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Cursor Right (TAB 11): Move the cursor one position to the right, without
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erasing or chaning characters on the screen (note sending out
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SPACE - ASCII 40 does erase, so this is used to forward space
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without erasing). In the last column, this causes wraparound
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to the next line, column 0. On the last line of the screen,
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wraps to the top line or scrolls depending on the page mode switch.
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Cursor Up (SO 16): Moves the cursor up one line, maintaining the
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same horizontal position (like line starve or inverse linefeed).
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On the top line, the cursor does not move (i.e. this is a no-op)
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Cursor Address (SI 17): Absolute cursor position. The next two characters
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specify the column and line of the cursor position, respectively.
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The column character is computed by <c/10.>_4 + <c-<c/10.*10.>>
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where c is the column number (origin 0) - this is sort of BCD like.
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The row character is simply the row number (origin 0) + 100 (octal)
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Thus 0,0 is ^O^@@ and 23.,79. is ^OyW
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Don't have any information on keyboard characteristics for controllers that
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have them.
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