85,86



85,86          55,56          COLCRS
     Current graphics or text mode cursor column; values range from
     zero to 319 (high byte, for screen mode eight) depending on
     current GRAPHICS mode (maximum numher of columns minus
     one). Location 86 will always be zero in modes zero through
     seven. Home position is 0,0 (upper left-hand corner). Columns
     run vertically from the top to the bottom down the TV screen, the
     leftmost column being number zero, the rightmost column the
     maximum value in that mode. The cursor has a complete top to
     bottom, left to right wraparound on the screen.

     ROWCRS and COLCRS define the cursor location for the next
     element to be read from or written to in the main screen segment
     of the display. For the text window cursor, values in locations 656
     to 667 ($290 to $29B) are exchanged with the current values in
     locations 84 to 95 ($54 to $5F), and location 123 ($7B) is set to 255
     ($FF) to indicate the swap has taken place. ROWCRS and
     COLCRS are also used in the DRAW and FILL functions to
     contain the values of the endpoint of the line being drawn. The
     color of the line is kept in location 763 ($2FB). These values are
     loaded into locations 96 to 98 ($60 to $62) so that ROWCRS and
     COLCRS may be altered during the operation.

     BASIC's LOCATE statement not only examines the screen, but
     also moves the cursor one position to the right at the next PRINT
     or PUT statement. It does this by updating locations 84 and 85,
     above. You can override the cursor advance by saving the
     contents of the screen before the LOCATE command, then
     restoring them after the LOCATE. Try:

     100  REM: THE SCREEN MUST HAVE BEEN 0
         PENED FOR READ OR READ/WRITE PREV
         IOUSLY
     110  LOOK = PEEK(84): SEE = PEEK(85)
     120  LOCATE X,Y,THIS
     130  POKE 84, LOOK: POKE 65, SEE

     Note that CHR$(253) is a non-printing character---the bell--
     and doesn't affect the cursor position.

     See COMPUTE!, August 198l, for an example of using COLCRS
     for dynamic data restore and updating with the screen editor and
     the IOCBs.

87             57             DINDEX
     Display mode/current screen mode. Labelled CRMODE by (*M).
     DINDEX contains the number obtained from the low order four
     bits of most recent open AUX1 byte. It can be used to fool the OS
     into thinking you are in a different GRAPHICS mode by