Erik, wonderfull work. So Sprite re-definition mid-screen is possible. Fast rate video slo-mo of the screen is amazing!
The PC1 have 2 x 4416 DRAM - giving us 16KB RAM (4 x 16.384 bit x 2 chip = 16kByte), but hey we can change with 4464 and have plain 64kB!
Actually I'm trying something more complex like 640x200 x 16 color with i.e. ESP32. And unlocking also 640x400 with per-frame page change...