Popular Computing Weekly 30/06/1983 Pages 9 & 10

Space Docking

A new game for 16K ZX Spectrum by Colin Jones

Your on-board computer has locked on a satellite that, after 10 years in parked
orbit around the Earth, is to be retrieved for routine servicing.

You are aware of a knot of tension in the pit of your stomach as you take the
controls of the huge space shuttle, preparatory of making the fine
synchronisation adjustments necessary for successful docking. The grim
concentration on your face is a cold blue, lit by the flickering light emitted
by your data screen. The screen shows an image constantly changing as the
satellite moves through space.

The gleaming shuttle ponderously rotates towards the tiny fragile satellite as
you use the side thrusters to match the spin. As the screen indicates that you
have achieved synchronisation, you nudge your shuttle forward.

A huge image now fills the screen to indicate your proximity to the satellite.
You are within seconds of final dock. Panic tries to seize you! You see that
the satellite has suddenly started to drift away from you! Have you the time to
match the new spin before you collide?

Use cursor keys to control the shuttle

5 -- Rotate/Spin Left
6 -- Move Backwards
7 -- Move Forwards
8 -- Rotate/Spin Right

Commentary

35-60		Set variables
70-90		Screen display
100-160		Read keyboard
170-260		Display indicators (distance/spin sync/time left)
270-290		Display new satellite image
300-340		Set spin factors
350-450		Remove old satellite image/calculate new image
370		NOTE -- To test 'docking complete' sequence
460-490		Calculate new spin/approach factors
500-530		Docking complete
540-600		Score/new satellite?
610		Ran out of time
620		Crash

Variables

L -- cumulative score
j -- time remaining
P -- horizontal line of sat image
I -- input from keyboard
K -- spin display position
RA -- Rate incr.decr distance from sat
R -- size of sat image
RT -- rate spin incr/decr