sometimes99er Posted December 5, 2010 Share Posted December 5, 2010 Here's one Marc wrote: LI R0,>9F00 MOVB R0,@>8400 That part is dealing with the sound-chip, so it's not relevant to VMBW. Obviously Matthew's is dependant on other VDP routines he wrote, but I have them all in the Beryl scroller that he sent me. It's really interesting to read through that source... just so neat and clean. =) Yes, often you'll discover, that you will help yourself to better and more quickly reread/understand and debug your own code, if you have a lot of comments like that. I'm studying "ORI" right now.... Looks like it compares two words and sets the bits to the new word if either of the bits are set in either of the compared words. Yes, a bit set in either will set a bit in the "output". The comment "Set read/write bits 14 and 15 to write (01)" might be slightly off (no big deal). The assembler instruction is "just" setting bit 14 and not carrying about the state of bit 15. We must assume bit 15 to be 0 to get to 01. I don't know if 11 will work. The three possible commands should be, write to register (10), set address for write (01), and set address for read (00). Quote Link to comment Share on other sites More sharing options...
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