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Toni Wilen · 22 January 2018, 20:41

I think this is now completely solved. Undefined = BPLCON2 PF1 and/or PF2 is set to undocumented value 5, 6 or 7. OCS/ECS only.

Sprites and sprite priorities work identically to documented value 4 (all sprites have priority over both playfields) even if value is 5 or larger.

Normal plane mode and EHB:

If number of planes is 5 or 6 and BPLCON2 PF2 is >= 5 and if plane 5 (counting from 1) has bit set: other planes are ignored in palette selection = COLOR16 is selected. ("SWIV" score board feature). PF1 does nothing.

Dual playfield:

Any number of planes. No 5+ requirement here.

If playfield's matching BPLCON2 PFx value is >=5 and if playfield is not transparent, it is always drawn using COLOR0. PF2PRI still work normally, only color selection becomes strange. (Used in Running man / Scoopex intro's logo). If both PF1 and PF2 is >=5: both playfields disappear, only background color (and sprites) are visible.

HAM:

HAM works normally. EDIT: Most likely because "special" plane 5 is is not used in HAM to select palette indexes.

22 January 2018, 20:41	#227
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,507	BPLCON2 undefined behavior I think this is now completely solved. Undefined = BPLCON2 PF1 and/or PF2 is set to undocumented value 5, 6 or 7. OCS/ECS only. Sprites and sprite priorities work identically to documented value 4 (all sprites have priority over both playfields) even if value is 5 or larger. Normal plane mode and EHB: If number of planes is 5 or 6 and BPLCON2 PF2 is >= 5 and if plane 5 (counting from 1) has bit set: other planes are ignored in palette selection = COLOR16 is selected. ("SWIV" score board feature). PF1 does nothing. Dual playfield: Any number of planes. No 5+ requirement here. If playfield's matching BPLCON2 PFx value is >=5 and if playfield is not transparent, it is always drawn using COLOR0. PF2PRI still work normally, only color selection becomes strange. (Used in Running man / Scoopex intro's logo). If both PF1 and PF2 is >=5: both playfields disappear, only background color (and sprites) are visible. HAM: HAM works normally. EDIT: Most likely because "special" plane 5 is is not used in HAM to select palette indexes. Last edited by Toni Wilen; 23 January 2018 at 12:23.