Version analysis of me2 - Elite on the 6502

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

Cassette, Disc (flight), Disc (docked), 6502 Second Processor, Master and Electron

Code variations between these versions are shown below.

       Name: me2
       Type: Subroutine
   Category: Flight
    Summary: Remove an in-flight message from the space view


.me2

Code variation 1 of 2Related to the Master version

The Master version clears the bottom part of the screen when displaying in-flight messages in screens other than the space view, whereas the other versions messily superimpose the message over the current screen.

See below for more variations related to this code.

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

Master
 LDA QQ11               \ If this is not the space view, jump down to clynsneed
 BNE clynsneed          \ to skip displaying the in-flight message

 LDA MCH                \ Fetch the token number of the current message into A

 JSR MESS               \ Call MESS to print the token, which will remove it
                        \ from the screen as printing uses EOR logic

 LDA #0                 \ Set the delay in DLY to 0, so any new in-flight
 STA DLY                \ messages will be shown instantly

 JMP me3                \ Jump back into the main spawning loop at me3

Code variation 2 of 2Related to the Master version

See variation 1 above for details.

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

Master
.clynsneed

 JSR CLYNS              \ Clear the bottom three text rows of the upper screen,
                        \ and move the text cursor to the first cleared row

 JMP me3                \ Jump back into the main spawning loop at me3