Peripheral 4 Register

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Number $09
Readable Yes
Writable Yes
Short Description Sets scanlines, AY mono output, Sprite-id lockstep, disables Kempston and divMMC ports.
Bit Function
7 Enables AY2 "mono" output (A+B+C is sent to both R and L channels, makes it a bit louder than stereo mode).
6 Enables AY1 "mono" output (1 = mono, 0 default)
5 Enables AY0 "mono" output
4 Sprite id lockstep (1 = Sprite port-mirror Index Register ($34) and Sprite Status/Slot Select ($303B) are in lockstep, 0 default)
3 (core 2.0) Disables Kempston mouse port ($DF) if set

(core 3.0) 1 to reset mapram bit in divmmc

2 (core 2.0) Disables divMMC ports ($E3, $E7, $EB) if set

(core 3.0) Reserved, use 0

1-0 scanlines configuration (0 after a PoR or Hard-reset):

%00 = scanlines off, %01 = scanlines 75%, %10 = scanlines 50%, %11 = scanlines 25%