Some experiments with mid-screen mode switching on the Apple IIe.
Was initially trying some vaporlock for the AppleIIbot but forgot the
emulator used there (linapple?) doesn't implement the VBLANK register,
or mid-screen mode switching.
Further work in this directory is looking at more advanced switching
of the double modes (80-column, double-lores, double-hires) as well as
messing with the AN3 setting.
SPLIT -- tiny apple IIe mode switch code
NOVBLANK -- apple IIe mode switch that doesn't wait for VBLANK
DOUBLE -- test of mid-screen switch of double modes
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