Parameters for DrawPicture, read and written through IY. BASIC only POKEs the picture number here; *DrawPicture_Third and *DrawPicture_Thirds are always FF in the snapshot, so the routine takes the screen third and the number of thirds from the picture record.

The flags at DrawPicture_Flags:

Bit	Relating To
00	Pixel data order (set: rows; clear: columns)
02	Set while a run of repeated bytes is being written
03	Set while the attributes are being drawn

Parameters for DisplayFrame.

Parameters for ScrollWindow.