MILKY WAY

by Neil Hopkinson

from Your Sinclair #32 (August 1988)

[files MILKYWAY.*]



Yes, the routine which doesn't ruin your appetite (though it might make

you feel space-sick). Here as promised last month is a four-directional,

3D, interrupt driven, sit up and beg star routine, courtesy of a very

able Neil Hopkinson. And what's more, the whole program he's sent in is

self-contained, which makes my job easier and your job simpler.



Points



Ouch! They're sharp. Nope, seriously folks, here are some points I feel

I must make concerning this fabbaroony routine:

1. If you've got a 128K, ask yourself why and then remember to use this

program in 48K mode only.

2. Printing, clearing the screen, or making funny noises is not

recommended while this program is running, unless accompanied by a

responsible adult.

3. The program uses Interrupt Mode 2, so interrupts should not be

disabled.



They were the warnings and now for the hi-tech, brain-blending info:

a) The 45 stars are stored from 64376 to 64468 in the format: X co-ord,

Y co-ord.

b) The code starts at 64000 and is 512 bytes long.

c) To get the stars going, either use a korma curry or RANDOMIZE USR 64000.

d) To stop the stars going, either use a bung or RANDOMIZE USR 64003.

e) You can change the amount of stars per field (currently fifteen), by

POKEing 64334, number of stars. But don't put in more than 15.



Interrupts? What The - ?



Again, it's time for me to adopt my machine code drone voice and tell

you what interrupts are. Interrupts are specialised instructions that,

when used correctly, can enable you to run two programs simultaneously.

What you see is actually an illusion; the computer is just jumping

between the two routines every 50th of a second, so it only seems like

the two are running together. They are especially useful when used with

Basic as they allow the user to run a machine code routine and type in

Basic or whatever.



The Program



Here it is, and there it isn't. It's not that long considering the

effect it gives. Save it with: SAVE "stars" LINE 10 and you're awayyy!