HOPPER for Sinclair ZX-81
by Stuart Nicholls
from Your Computer, November 1982 & January 1983

If you have a RAM pack you will need to remove it, or reset RAMtop to less
than 3.25K.

The object of the game is to hop your frog, an inverse *, across the road,
avoiding all the obstacles, to the safe middle island, then hop on to the
lily pads represented by 0s and logs represented by #s [graphic 83 hex] and
finally into one of the four homes. Each home is repesented by a *.

The frog is controlled by pressing key 5 to go left, 8 to go right and 0 to
go up. Each move up is counted, and a time limit of 199 seconds [game
actually uses 299] is given in which to fill all four home bases. If a frog
is hit on the road, jumps into the lake, hits a wall or floats off the
screen on a lily pad or log, then it is dead, and another frog is given at
the base line. You cannot hop the frog off the screen.

The game finishes when all four home bases are filled or when the counter
reads zero. the aim, therefore, is to fill all home bases in the quickest
time, with the least number of up hops.

[The program bytes listed in January 1983 contain 4 bugs:
 - Instruction 'LD (16445),HL' (bytes 22 3D 40) missing at 16855.
 - Instruction byte for 'OR E' at 16974 listed as 'BC' instead of 'B3'.
 - Instruction bytes for 'JR NZ,-5' at 16975 listed as 'Z + * FB' instead
   of '20 FB'.
 - Instruction bytes for 'LD HL,(D-File)' at 16987 listed as '2A 0C 49'
   instead of '2A 0C 40'.]
