FROGGIE for Sinclair ZX-81
by Richard Braunton
from Your Computer, February 1984

R Braunton gives you a leaping game for a leap year.


Froggie is a version of the well known arcade game for the 16K ZX-81
with these features:
* Fast machine code action;
* Moving cars, lorries and racing cars;
* Moving logs and turtles;
* Alligators and diving turtles;
* Flies and alligators in the homes;
* Snake on the bank;
* Baby frog to rescue;
* Time bar;
* Extra frog at 8000 points;
* Hold key.

The machine code itself is stored in a REM 6208 bytes long. This is
obtained by entering the first line:
	 1 REM 153 characters
Then edit the line and change it to line 2, then edit this and change
it to line 3. Carry on this procedure until you have lines 1 to 39.
Then add:
	40 REM 6 characters
and then enter the following commands:
	POKE 16510,0
	POKE 16511,65
	POKE 16512,24

This will result in all the REMs becoming one large REM of 6208
characters. Now type in the hexadecimal loader, program 1. Run it and
type in the machine code but missing out the first column as this is
the address at which the code is stored. The numbers are entered from
left to right and can be either entered one by one of a number of them
together, but they must be entered as pairs and not as single
characters. Once the machine code has been entered, type S to stop the
program and then SAVE the program a few times on tape.
[These instructions are wrong for the hex loader which was actually
printed in the magazine. JimG]

Then type the following lines:
	10 SAVE "FROGGIE"
	20 LET L=USR 22160
	30 CLS
Now type GOTO 20. If the program runs as described later in the
article then delete the loader program and run the program to SAVE it.
If not then enter program 2, substituting the addresses between which
you wish to check for Start and Finish. Type RUN 9900 and check that
it agrees with my listing. Then you can correct any mistakes you find
by changing the value of A in line 100 to the offending address and
enter the correct number. [Again, this does not match the hex loader
printed (line 100 is a CLS). JimG] Note that the bytes up to address
16560 need not be 0 as these locations are used as stores and will
alter after the program has run once.

On running the program there will be a title sequence telling you to
press a key. You control the frog - an inverse X - using the four
cursor keys. The object is to fill the homes at the top of the screen.
To get there you must avoid the traffic on the road and jump onto the
logs and turtles to cross the river, but watch out for the diving
turtles and alligators. You are racing against time which is shown at
the bottom of the screen and you will gain a bonus for the time
remaining after filling a home.

On the first sheet there isn't very much traffic and there are many
logs and turtles, but as you go through more sheets there are less and
shorter logs and more traffic including fast racing cars after the
second sheet. A snake - an inverse S - patrols the banks after the
first sheet.

On the first sheet there are also flies - inverse Fs - which appear in
the homes occasionally and can be eaten for extra points. But after
the first sheet alligators appear in the homes and must be avoided
when they are fully in the home. You can also rescue a baby from for
extra points.

Scoring is as follows:
	Jumping forward          10
	Jumping backwards        -10
	Filling one home         100
	Filling all five homes   1000
	Baby frog                50
	Flies                    50
You also score 10 times the amount of time you have left after filling
a home. The game can be held by pressing H and started again by
pressing S.

It is a little difficult to get into the leftmost home at first but
becomes easy after a few games. To get in you must do two quick hops
off the turtles onto the logs and into the home just as the turtle
moves you onto the far left position.

