After 30 years, thanks to Analmux, we have the perfect PMG routine for Turbo-Basic XL (and Atari Basic).
I have tried many important routines (from magazines and books) but they all have problems or limitations (flicker, players height, number, resolution, no flicker-free multicolor, not compilable with TBXL).
http://www.atariage.com/forums/topic/149441-multipurpose-pm-engine-for-use-in-basic/