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⌂ ∞ ▽ Elite on the 6502

Drawing the screen: TRADEMODE

[6502 Second Processor version]

       Name: TRADEMODE                                               [Show more]
       Type: Subroutine
   Category: Drawing the screen
    Summary: Clear the screen and set up a printable trading screen

    Context: See this subroutine in context in the source code
 Variations: See code variations for this subroutine in the different versions
 References: This subroutine is called as follows:
             * EQSHP calls TRADEMODE
             * STATUS calls TRADEMODE
             * TT167 calls TRADEMODE
             * TT208 calls TRADEMODE
             * TT213 calls TRADEMODE
             * TT219 calls TRADEMODE
             * TT25 calls TRADEMODE




 Clear the top part of the screen, draw a border box, set the print flag if
 CTRL is being pressed, set the palette for trading screens, and set the
 current view type in QQ11 to A.



 Arguments:

   A                    The type of the new current view (see QQ11 for a list of
                        view types)



.TRADEMODE

 PHA                    \ Store the view type on the stack so we can restore it
                        \ after the call to CTRL

 JSR CTRL               \ Scan the keyboard to see if CTRL is currently pressed

 STA printflag          \ Store the result in printflag, which will have bit 7
                        \ set (and will therefore enable printing) if CTRL is
                        \ being pressed

 PLA                    \ Restore the view type from the stack

 JSR TT66               \ Clear the top part of the screen, draw a border box,
                        \ and set the current view type in QQ11 to A

 JSR FLKB               \ Call FLKB to flush the keyboard buffer

 LDA #48                \ Send a #SETVDU19 48 command to the I/O processor to
 JSR DOVDU19            \ switch to the mode 1 palette for trading screens,
                        \ which is yellow (colour 1), magenta (colour 2) and
                        \ white (colour 3)

 LDA #CYAN              \ Send a #SETCOL CYAN command to the I/O processor to
 JMP DOCOL              \ switch to colour 3, which is white in the trade view,
                        \ and return from the subroutine using a tail call