HI-RES SKYSCRAPER
Alan Lee, Tring, Hertfordshire
from Your Computer, June 1985

THIS IS a version of the popular game in which 
a spaceship continually passing over a city has 
to flatten the buildings in order to clear a land- 
ing strip. The spaceship gets lower on each 
pass and vaporises if it hits a building. If the 
ship lands successfully you move on to another 
screen of buildings, but the ship moves faster, 
and starts off one line lower than before. 

A point is scored for each building block 
knocked out, the score is shown in the top-left 
corner. A bomb is released by pressing any key, 
though only one bomb can be in the air at any 
time. To restart the game after the ship crashes, 
press any key. 
The program is 818 bytes long. To create a 
Rem statement large enough type in: 
1 REM * * 160 characters * * 
Edit this line four times to create lines 2-5. 
Then enter: 

POKE 16511,58 
POKE 16512,3 
POKE 16514,118 
POKE 16515,118 
Then enter a line 6 Rem newline, followed 
by 
POKE 16419,6 

This line is needed to prevent the ZX-81 going 
into an infinite scrolling loop when the hex 
loader is deleted - do not remove it at any 
time. Now enter the standard YC hex loader 
and enter the machine code in the usual way. 
Then save the program a couple of times, and 
run it using Rand USR 16993. If it works 
correctly enter the following lines: 
10 SAVE "SKY" 
20 RAND USR 16993 

and run it to create a final copy which runs 
automatically on loading. You will have to 
switch off the machine and reload to do this, as 
the program is a continuous machine-code 
loop. If the program does not work correctly, 
again switch off the machine, reload, and enter 
a standard hex-checker to find the errors in the 
machine code. 

The program will not work if a peripheral is 
attached which lies in the 8K-16K area of 
Rom. 
