Peripheral 2 Register

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Number $06
Readable Yes
Writable Yes
Short Description Enables Acceleration key, DivMMC, Multiface, Mouse and AY audio.
Bit Function
7 Enable turbo mode key "F8", 0 = disabled (1 after Soft-reset)
6 core3.1.2: Divert BEEP-only to internal speaker (hard reset = 0)

DMA mode (0 = zxnDMA, 1 = Z80 DMA) (0 after Hard-reset)

5 Enable "F3" key (50/60 Hz switch) (1 after Soft-reset) (was "Enable Lightpen" in core 2.0)
4 Enable DivMMC automap and DivMMC NMI by DRIVE button (0 after Hard-reset)
3 Enable multiface NMI by M1 button (hard reset = 0)
2 PS/2 mode (primary device: 0 = keyboard, 1 = mouse), exchanges the keyboard/mouse pins on the PS/2 connector (writeable only in config mode)
1-0 Audio chip mode (%00 = YM, %01 = AY, %1x = Disabled)

(core 3.0) %11 hold all AY in reset

The bit 7 doesn't prevent SW from setting up turbo mode by writing into Turbo Control Register ($07), it is used only to enable/disable the "F8" key toggle, similarly bit 5 enables "F3" key.

NEW in core 3.0:

 bit 5 = enable F3 (50/60 Hz)
 bit 2 ps2mode only modifiable in config mode
 chip mode = 11 resets all AY

NEW in core 3.1.2:

 bit 6 = BEEP-only into internal speaker (DMA does use two I/O ports now)