For 16K machines

Someone had asked if this would run on an Atari 400 w/ 16KB ram. I assumed 48K when I coded this, so lazily used higher memory locations for screen and charset.  Today I modified the memory locations to fit within 16K (i just barely had room) and tested it in Altirra.  It is otherwise identical (still fits in 10 lines). Download here to try on your 400 16K:

https://www.carr-designs.com/downloads/TETRIS.XEX