- Joined: 28 Sep 1999
- Posts: 1197
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SG-1000 stuff
 Posted: Sun Aug 27, 2000 2:32 am
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I've got a few questions about the SG-1000, maybe some of you might have answers.
- What is in the memory area of 8000-BFFF? The main 8K of RAM mirrored twice? Maybe some part of the ROM is mirrored there?
- When is the fifth sprite flag cleared?
- Does reading the control port have any affect of the fifth sprite number bits? Or should I assume those bits are always of the 5th sprite / last sprite in list / last sprite with a Y pos. of 208?
- It seems that the vertical interrupt can occur multiple times from line 192 onward, providing the control port isn't read. Up to what line does this go until? Line 262? Line 0? Some other weird value like line 224?
- Any ideas on what happens if an 8x16 or 16x16 sprite uses the last pattern in the pattern table, which is at the very end of VRAM? I'm thinking the remaining patterns might be fetched from VRAM address zero, or from the very start of the pattern table..
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