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Added DTV detection code by Marco van den Heuvel.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4580 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2010-02-04 20:27:48 +00:00
parent aa6a507991
commit e65f966d25
1 changed files with 22 additions and 2 deletions
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24
libsrc/c64/dtv-himem.s
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@ -5,10 +5,12 @@
; Ullrich von Bassewitz, 2005-11-27
;
.include "zeropage.inc"
.include "em-kernel.inc"
.include "em-error.inc"
.import _get_ostype
.macpack generic
@ -71,8 +73,26 @@ curpage: .word $0000 ; Page
;
INSTALL:
lda #$01
sta $d03f ; Enable extended register access
; Check for a DTV
ldx #1
stx $d03f
ldx $d040
cpx $d000
bne @present
inc $d000
cpx $d040
beq @present
dec $d000
; DTV not found
lda #<EM_ERR_NO_DEVICE
ldx #>EM_ERR_NO_DEVICE
rts
@present:
ldx #$FF
stx curpage+1 ; Invalidate curpage
inx ; X = 0