
Battle (aka. Crocodile Menace)
from Sinclair Programs, April 1985

Aaaargh! On your screen you see the ship of the evil Baron von Crocken.
On board that ship is the lethal purple spotted crocodile which he hopes
will help him in his ruthless bid to take over the country. Only you can
save all that is dear to you by shooting down the ship and the purple
spotted crocodile it contains. Move your gun sights up with 1, down with
A and fire with P.

Crocodile Menace was written for the 16K ZX-81 by Jason Singleton of
Dibden, Southampton.


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BINARY

VARIABLES
A variable is a name given to a location in memory to store a number. The 
value of a variable may change as the program is run, so the Spectrum 
changes the contents of memory locations to suit. There are just a few 
variables used in Binary: a description of each will help you to understand 
how it works:

n is the decimal to be converted to binary, though this is changed by the 
program as you will see.

col is the column number at which the program has to print the current 
binary digit.

a$ is a string variable, so called because is can hold a string of characters 
(still interpreted as numbers as far as the computer is concerned). In this 
program, it is used simply to hold the user's yes or no reply for another number.

HOW IT WORKS
The binary form for a decimal number is found by adding 1+2+4+8+16+32......2^n. 
This is the same as saying 2^0 + 2^1 + 2^2 + 2^3 + 2^4 + 2^5......2^n. 
(n in this case is the number of times we need to continue to keep multiplying 
by 2 to get the decimal we want to convert, NOT the decimal itself). For 
example, the decimal number nine would be 2^0(=1)+2^3(=8) and so the binary 
form is 1001. The conversion using a program is quite simple once you 
understand the principle as it is just a matter of continually dividing 
the number by 2 and checking to see if there is any remainder, in which 
case we put a one (otherwise zero). Take the number nine again. The first 
time we divide by two we get a remainder so we write down a 1 at the right-
hand side. Ignoring this remainder, we take the whole number of times we 
were able to divide by 2 (i.e. 4) and repeat the process. This time, we 
get 2 with no remainder, so we write down 0. Next time we divide we get 
1, again with no remainder, so we write down another 0. Finally, we get 
zero (which means we can go no further) but this time with a remainder, 
so the last number we write down is 1. Before trying to understand the 
program, make sure you understand how to do the conversion with pencil 
and paper on a few other numbers.

Lines
10		Sets screen colours and clears.
12-13		Print title etc.
20		Prompts for decimal number n to be converted. Note how 
		POKE 23617,158 (system variable for cursor mode) can be 
		used to obtain a flashing black square.
25		Sets up for printing at the right hand side of the screen 
		to start.
30		Confirms the number to be converted. Note how INT is used 
		to make sure that the user realises that the program will 
		only convert the integer part of the decimal number.
45-60		This is the loop which simulates the process we have just 
		looked at. Line 45 can only print 1 or 0 (for remainder or 
		no remainder). Line 50 resets n to the number of whole 
		divisions by 2 and moves "col" to print in the next 
		character position to the left (on row 15). Line 52 is the 
		means by which the program escapes from the loop when there 
		is nothing left to divide further.
200-215		Find out whether another number is to be entered.
9999		Saves and verifies "Binary" on cassette for you to use any 
		time you need to perform binary conversion.


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CHIP SHOP

Life is hard, working the Chip Shop. There are bugs everywhere, your boss 
is mean, and you hate your job. One day you ask for promotion. "Collect 20 
chip packets in 350 seconds," scowls your boss, "and promotion is yours." 
Of course, he knows just as well as you do that, almost as soon as the 
packets touch the floor, they are carried away by the bugs. Can you earn 
promotion?

Written for the Spectrum by Wayne Vaughan and Michael Nelson 
of Wednesfield, Wolverhampton.


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Heroic Hubert and the Caverns of Fire
from Sinclair Programs, April 1985


Heroic Hubert is an animated text adventure written by Darren Wombwell
of Skegby, Nottingham. [It's not a text adventure. JimG]

In it, you play the role of the intrepid hero, Hubert, who must cross
the Caverns of Fire in search of the Fire Rings. On the way he meets
many terrors: swinging spiders, perpetual flames and flying vampire
bats. There are pits in which he can hide, steps to negotiate, and
ropes on which he can swing to safety. He is also racing against the
clock, and the time is shown slowly ticking away. Hubert moves left
with key p, right with key o and climbs with key z. He will jump to the
left with O, and to the right with P.

Due to the complexity of this program, it will only RUN on the 48K
Spectrum.


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