catrainbow.bas for ti99/4a try it out on http://js99er.net/

catrainbow.bas

10 call clear
11 randomize

100 rem cat sprites
101 c$="4163777F6B6B3E1C"
110 for a=0 to 15
111 call char(a*8+32,c$)
112 next a

120 rem first rainbow characterset
121 for a=1 to 16
125 fg=int(15*rnd)+2
126 bg=int(15*rnd)+2
130 call color(a,fg,bg)
131 next a

140 rem random cats on screen
141 for row=1 to 24
142 for col=1 to 32
150 cat=int(16*rnd)*8+32
155 call hchar(row,col,cat)
160 next col
161 next row

170 rem random rainbow loop
171 for a=1 to 16
175 fg=int(15*rnd)+2
176 bg=int(15*rnd)+2
180 call color(a,fg,bg)
190 next a
195 goto 170