Sliding Block Puzzle (aka. Picture Slide) A variation on those sliding block puzzles you find in Christmas stockings, Picture Slide uses an impressive machine-code routine to swap areas of the screen display. Written by Pete Cooke of Leicester for the 16K Spectrum, it uses a simple picture located at lines 8210-8240. If you want you can adapt the program to draw your own picture, or even use a professional draw program to create a picture.