Commodore Amiga A2000 - Maximum Display Window Size; Figure 3-22 Display Window Vertical Stopping Position; Table 3-13 Maximum Allowable Vertical Screen Video

FULL SCREEN AREA
--------------------------------------------- 0
| |
| _________________________________|___128
| Vstop of display |
| window occurs in |
| the region. | (NTSC)______|___262
| | |
| | |
---------------------------------------------
Figure 3-22: Display Window Vertical Stopping Position
To set the display window stopping position, write HSTOP into bits 0 through 7 and VSTOP
into bits 8 through 15 of DIWSTOP.
MAXIMUM DISPLAY WINDOW SIZE
The maximum size of a playfield display is determined by the maximum number of lines
and the maximum number of columns. Vertically, the restrictions are simple. No data can
be displayed in the vertical blanking area. The following Table shows the allowable vertical
display area.
Table 3-13: Maximum Allowable Vertical Screen Video
Vertical Blank NTSC PAL
Start 0 0
Stop $15 (21) $1D (29)
NTSC NTSC PAL PAL
Normal Interlaced Normal Interlaced
Displayable lines
of screen video 241 483 283 567
=525-(21*2) =625-(29*2)
Horizontally, the situation is similar. Strictly speaking, the hardware sets a rightmost limit
to DDFSTOP of ($D8) and a leftmost limit to DDFSTRT of ($18). This gives a maximum of
25 words fetched in low-resolution mode. In high-resolution mode the maximum here is
49 words,
- 74 Playfield Hardware -