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Elite on the BBC Micro

Utility routines: TRADEMODE [6502SP version]

Name: TRADEMODE [Show more] Type: Subroutine Category: Utility routines 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 white border, 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 white border, \ 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