MaPa Posted February 14, 2008 Share Posted February 14, 2008 (edited) Hi, I'm just curious as I don't have real ATARI. Is the address after JVB (jump and wait for vertical blank interrupt) really needed or it just waits for VBI and after it it just starts DLI from address you defined in DLIST registers ($D402,3 or shadow regs $230,231) ? In emulator I didn't noticed any difference if I put after JVB instruction LSB and MSB of DLIST starting address or random data, zeros etc. it works just fine. Edited February 14, 2008 by MaPa Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted February 14, 2008 Share Posted February 14, 2008 maybe you haven't seen a difference because the system vbl is restoring the dlist vector... Quote Link to comment Share on other sites More sharing options...
NRV Posted February 14, 2008 Share Posted February 14, 2008 hmmm.. good question I believe that I had used chained display lists in some project many years ago (JVB of DL1 points to DL2, and JVB of DL2 points to DL1..) and it worked, but I don't know what happens in the emulator anyway, if you have the OS VBI active, maybe the process that copies the shadow register ($230,1) to the rom register ($D402,3) resets the address used in the JVB?? NRV Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 14, 2008 Share Posted February 14, 2008 The OS does it for you, but there's no guarantee it'll do it every time since it's in VBlank Stage 2. Just put random data in the address, then press some keys - about 1 in 10 or so, you'll get garbage or a blank screen flashing. Quote Link to comment Share on other sites More sharing options...
Sheddy Posted February 16, 2008 Share Posted February 16, 2008 I believe that I had used chained display lists in some project many years ago(JVB of DL1 points to DL2, and JVB of DL2 points to DL1..) and it worked, but I don't know what happens in the emulator I can confirm chained display lists work correctly in Atari800WinPlus 4 at least Quote Link to comment Share on other sites More sharing options...
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