====== DTV detect ======
Also detects C64 vs C128, and PAL vs NTSC.

<code>
;----------------------------------------------------------
; DTV detect v1.0 by TLR (disassembly by groepaz)
;
; returns:
;
; a=$7f c64
;   $ff c128
;   $7d dtv1 (ntsc dtv)
;   $75 dtv2 (early pal dtv)
;   $74 dtv3 (recent pal dtv, hummer game)
;
; x=0 ntsc
;   1 pal
;----------------------------------------------------------
dtvdetect:

        PHP
        SEI

        LDA #$00
        STA $FB
        STA $FC

        LDX #$FE
        CPX $D030
        ROL $FB
        STA $D03F
        JSR ic03e

        LDA #$01
        STA $D03F
        JSR ic03e

        LDA $FB
        CMP #$3A
        BNE skp1
        JSR ic067
skp1:
        ROL $FB
        LDA #$00
        STA $D03F

        ; test pal/ntsc
        JSR palntsc
        ROL $FC

        PLP
        LDA $FB
        LDX $FC
        RTS

;----------------------------------------------------------
	!scr "TLR'06"	; signature, not used
;----------------------------------------------------------

ic03e:
        LDY #$D0
        LDX #$40
        JSR ic04e
        LDX #$80
        JSR ic04e
        LDY #$D3
        LDX #$00
ic04e:		
        STY cmphi
        LDA #$55
lp1:
        STA $D000
cmphi=*+2
        CMP $D300,X
        BNE skp2
		
        EOR #$FF
        CMP #$55
        BNE lp1
ic061:	
        ROL $FB
        RTS
skp2:
        CLC
        BCC ic061
;----------------------------------------------------------
ic067:
        LDX #$1F
        STX $FF
lp2:
        LDA ic086,X
        STA $D320,X
        DEX
        BPL lp2

        LDA #$0F
        STA $D33A
lp3:
        LDA $D33F
        LSR A
        BCS lp3

        LDA $FF
        BEQ skp3
        RTS
skp3:
        SEC
        RTS

ic086:
	!byte $89,$c0,0,0, 0,0,0,0
	!byte 0,0,0,0, 0,0,0,0
	!byte $ff,0,0,0, 0,0,0,0
	!byte 1,0,0,5, 0,0,0,0
;----------------------------------------------------------
palntsc:
		
lp4:
        LDA $D011
        BMI lp4
lp5:
        LDA $D011
        BPL lp5
lp6:
        LDA $D012
        CMP #$20
        BEQ skp4
		
        LDA $D011
        BMI lp6
        CLC 		; C=0 - ntsc
skp4:
        RTS
;----------------------------------------------------------
</code>