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Elite on the BBC Micro

Version analysis of me1

This code appears in the following versions (click to see it in the source code):

Code variations between these versions are shown below.

Name: me1 Type: Subroutine Category: Text Summary: Erase an old in-flight message and display a new one
Arguments: A The text token to be printed X Must be set to 0
.me1 STX DLY \ Set the message delay in DLY to 0, so any new \ in-flight messages will be shown instantly PHA \ Store the new message token we want to print

Code variation 1 of 2Specific to an individual platform

This variation is blank in the Cassette, Disc (flight), Disc (docked), 6502 Second Processor and Electron versions.

Master

LDA #YELLOW \ Switch to colour 1, which is yellow STA COL
 LDA MCH                \ Set A to the token number of the message that is
 JSR mes9               \ currently on-screen, and call mes9 to print it (which
                        \ will remove it from the screen, as printing is done
                        \ using EOR logic)

 PLA                    \ Restore the new message token

Code variation 2 of 2Specific to an individual platform

This variation is blank in the Disc (docked), 6502 Second Processor and Master versions.

Cassette, Flight, Electron

EQUB &2C \ Fall through into ou2 to print the new message, but \ skip the first instruction by turning it into \ &2C &A9 &6C, or BIT &6CA9, which does nothing apart \ from affect the flags
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