o Genlock audio is disabled.
o Light pen is disabled.
o Interlaced mode is disabled.
o External resynchronization is disabled. (genlock)
SELECTING HORIZONTAL AND VERTICAL RESOLUTION
Standard home television screens are best suited for low-resolution displays. Low-
resolution mode provides 320 pixels for each horizontal line. High-resolution monochrome
and RGB monitors can produce displays in high-resolution mode, which provides 640
pixels for each horizontal line. If you define an object in low-resolution mode and then
display it in high-resolution mode, the object will be only half as wide.
To set horizontal resolution mode, you write to bit 15, HIRES, in register BPLCON0:
High-resolution modewrite 1 to bit 15.
Low-resolution modewrite 0 to bit 15.
Note that in high-resolution mode, you can have up to four bit-planes in the playfield and,
therefore, up to 16 colors.
Interlaced mode allows twice as much data to be displayed in the same vertical area as in
non-interlaced mode. This is accomplished by doubling the number of lines appearing on
the video screen. The following Table shows the number of lines required to fill a normal,
non-overscan screen.
Table 3-6: Lines in a Normal Playfield
NTSC PAL
-----------------------
Non-interlaced 200 256
Interlaced 400 512
In interlaced mode, the scanning circuitry vertically offsets the start of every other field by
half a scan line.
- Playfield Hardware 43 -
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