If you are of my age you probably had one of these preciously locked away somewhere in your school and brought to the classroom for demonstrations. If you were really lucky you might even have been allowed to use it. Hopefully you didn't make a mistake and draw on the floor in permanent marker.
Instructions to reveal the co-ordinates of the final cache are below. These days you can even find pages on the web that will run the instructions in your browser. Which will definitely be much quicker!
CS PU LT 50 FD 250 RT 50 PD SETPENSIZE [3 3] FD 55 RT 150 FD 65
LT 150 FD 55 PU RT 90 FD 60 LT 180 PD FD 35 LT 90 FD 15 LT 90
FOR [i 1 90] [FD 1-(:i/90) RT 1] FOR [i 90 1] [FD 1-(:i/90) RT 1]
PU LT 180 FD 70 PD REPEAT 180 [fd 1 lt 2] PU FD 80 LT 90 PD FD 55
LT 150 FD 40 LT 120 FD 30 PU RT 30 FD 40 LT 120 PD FD 55 LT 90
FOR [i 1 90] [FD 0.75-(:i/120) LT 1] FOR [i 90 1] [FD 0.75-(:i/120) LT 1]
PU FD 10 PD FD 1 PU FD 10 LT 50 FD 45 RT 50 PD REPEAT 180 [fd 1 rt 2]
PU FD 50 PD REPEAT 90 [fd 0.5 rt 2] REPEAT 180 [fd 0.5 lt 2]
REPEAT 90 [fd 0.5 rt 2] PU FD 60 RT 180 PD FD 35 LT 90 FD 15 LT 90
FOR [i 1 90] [FD 1-(:i/90) RT 1] FOR [i 90 1] [FD 1-(:i/90) RT 1]
PU LT 10 FD 400 LT 80 PD LT 10 FD 55 LT 150 FD 20 RT 140 FD 20
LT 150 FD 55 PU RT 80 FD 40 PD
REPEAT 3 [PD REPEAT 180 [fd 1 rt 2] PU FD 65 PD]
FOR [i 1 90] [FD 0.75-(:i/120) RT 1] FOR [i 90 1] [FD 0.75-(:i/120) RT 1]
FOR [i 1 90] [BK 0.75-(:i/120) RT 1] FOR [i 90 1] [BK 0.75-(:i/120) RT 1]
PU FD 40 LT 60 PD FD 70 RT 60 BK 35 PU RT 35 FD 55 LT 35 PD FD 1 PU LT 70
FD 35 RT 160 PD FD 55 PU LT 90 FD 45 RT 180 PD FD 35 RT 140 FD 36
REPEAT 230 [FD 0.3 LT 1] PU LT 65 FD 87 RT 155 PD FD 35 RT 140 FD 36
REPEAT 230 [FD 0.3 LT 1] HT