|3||LK3|| rowspan="3" |Distributor ID, see [[LK-selectable Brand Names]] for details. Usually set to [[Amstrad]], [[Awa]], or [[Schneider]]||Purpose unknown (set to "1")
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|2||LK2||Manufacturer ID bit2||Purpose unknown (set to "0")
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|1||LK1||Manufacturer ID bit1||Expansion Port /TEST pin
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|0||[[CRTC]] VSYNC||Vertical Sync ("1"=VSYNC active, "0"=VSYNC inactive)||Same as on CPC