Hallo Patryk, > ... or is it already ashtrays.. ? To start with you last remark: AFAIK, dead. I have no experience with the VICE monitor but it loops from $E5E8 until $E5EF, a normal behaviour IMHO. > Did you triple-check if something could still possibly be > referencing an absolute location? ; set 60Hz and enable timer SetViaTimer: ; [FE39] lda #$C0 ; enable T1 interrupt sta VIA2_IER ; set VIA 2 IER nop nop nop nop lda #$26 ; set timer constant low byte [PAL] ; LDA #$89 ; set timer constant low byte [NTSC] sta VIA2_T1Cl ; set VIA 2 T1C_l The above works, the 1-3 combination I showed you in the previous email as well. The 2-2 combination goes wrong, as well as the 3-1 and 4-0 combination. That rules out any referencing to "lda #$26" and beyond because then it already should have go wrong above. If there is a weird direct JMP or JSR to 'sta VIA2_IER', I cannot see what wrong adding some extra NOPs would do. And indeed, one doesn't. But two do ??? But.... to make it weirder, while writing the above I got the idea starting to move the whole just one byte. Result: black screen. Uhhh ???? I experimented a bit and the following code still ends up in a black screen. ; set 60Hz and enable timer SetViaTimer: ; [FE39] lda #$C0 ; enable T1 interrupt sta VIA2_IER ; set VIA 2 IER lda #$26 ; set timer constant low byte [PAL] ; LDA #$89 ; set timer constant low byte [NTSC] sta VIA2_T1Cl ; set VIA 2 T1C_l nop lda #$48 ; set timer constant high byte [PAL] ; LDA #$42 ; set timer constant high byte [NTSC] sta VIA2_T1Ch ; set VIA 2 T1C_h rts But moving the NOP instruction behind 'lda #$48' ends up wit a normal functioning VIC-20. But four NOPs on that spot run fine. So what about one before and three behind 'lda #$48'? Black screen again. 2-2 and 3-1 on their turn run fine again. But I let it rest for the moment because the problem lays behind the BASIC/VIC-20 barrier. -- Kind regards / Met vriendelijke groet, Ruud Baltissen www.Baltissen.org Message was sent through the cbm-hackers mailing listReceived on 2013-06-29 16:00:05
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