Some more stuff for the ZX81

SINC ARTIST - A nice art program for the ZX81 must be loaded in two
              parts SINCART1.P and then SINCART2.P
ZX81.ROM    - need I say more
TREE4TH.ROM - A FORTH ROM for the ZX81 multi tasking, realtime clock
              for a 2K or greater ZX81/TS1000 system. If porting to
              a custom system beware of the fixed dfile location above
              32K which can cause problems with some decoding circuits.