Vic-20 Graphics Memory Layout
$1000-$10EF screen (240 bytes), values $10-$FF (16 to 255)$10F0-$10FF unused (16 bytes)$1100-$1FFF bitmap (3840 bytes)
BASIC RAM can be moved to either 3K expansion RAM ($400-$FFF) or 8K or greater expansion RAM ($2000 and later).
As the Vic-20 allows for configuring the number of character columns, character rows, and adjusting top and left margins, a variety of resolutions are possible.
160x192, 192x160, 200x144, 144x208, 160x160
The last is mentioned as it is the resolution used by the Super Expander cartridge. But note it only requires 200 bytes of screen memory, so using that resolution leaves 696 bytes of onboard memory unused for graphics/screen that could be available for another use, maybe 506 bytes is still text screen memory.