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⌂ ∞ ▽ Elite on the BBC Micro and NES

Utility routines: SwitchToFileSys

[Elite-A, Docked]

       Name: SwitchToFileSys                                         [Show more]
       Type: Subroutine
   Category: Utility routines
    Summary: Restore the filing system workspace to &C000 on a BBC Master

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * CHPR calls SwitchToFileSys
             * MEBRK calls via SwitchToFileSys+5




 Other entry points:

   SwitchToFileSys+5    Restore the workspace irrespective of the value of CATF



                        \ --- Mod: Code added for Elite-A: -------------------->

IF _BUG_FIX

.SwitchToFileSys

                        \ This routine restores the filing system workspace to
                        \ &C000 on a BBC Master, but only if CATF is non-zero
                        \ and we overwrote it in SwitchToCharSet
                        \
                        \ Call it at SwitchToFileSys+5 to restore the workspace
                        \ irrespective of the value of CATF

 LDX CATF               \ If CATF = 0, jump to file1, otherwise we are
 BEQ file1              \ printing a disc catalogue

 LDA #0                 \ Call OSBYTE with A = 0 and X = 1 to fetch bit 0 of the
 LDX #1                 \ operating system version into X
 JSR OSBYTE

 CPX #3                 \ If X =< 3 then this is not a BBC Master, so jump to
 BCC file1              \ file1 to continue drawing the character

 BIT wsstatecopy        \ If bit 7 of wsstatecopy is set then the character set
 BMI file1              \ was already present before this call, so skip the
                        \ following so we don't change that

 JSR restorews          \ Call restorews to restore the filing system workspace

.file1

 RTS                    \ Return from the subroutine

ENDIF

                        \ --- End of added code ------------------------------->