SPACE

It is stardate 2016

An arcade game for CBM 3016 and/or 3032 series computer.
Thomas Kneisel 1981

This is an old program I have written decades ago in assembly language. The only copy of the program was a hardcopy of a hexdump I had printed in June 1982 on my very last day in school.

When I discovered VICE emulator some sixteen years later, I started to type in the entire program, but soon I lost passion as well as confidence.
Again 16 years later I have now completed the work!

How to run the program

1) Start the Vice Emulator "xpet"
2) Change settings to model 3032 computer and 8050 floppy disk
3) Don't forget to deactivate warp mode.
4) Attach the floppy image "space.d80"
5) Type in LOAD "SPACE",8 to load program
6) launch program with RUN

The program is more or less self explaining, but the texts on the screen are in German.
You are sitting in a spaceship looking out of its front window. You can see stars passing by and sometimes enemy ships will come along. You can either destroy them or - when they pass your ship - it will cost you energy of your shields. If the shields are completely down, you will be dead.

You can destroy enemy ships by moving a crosshair over the screen. The number keys will start the crosshair moving, the "5" will stop movement. If you are pressing the space bar in the right moment, the enemy ship will explode and if it happens soon enough, your shields are saved.

Every shot will cost you some energy, but you can transfer energy from shields to canon and vice versa (keys "V" and "B")

Enemies, which were not destroyed,  will return somewhen later. To find out, from which direction the next enemies will approach, you can switch to a radar screen ("N"). "M" brings you back to the standard view.

(I have learned that the "M" key was a bad decision, because you cannot play the game on a computer without a separate numeric key pad, e.g. most notebooks. To move the crosshairs, you need to activate numlock and then "M" will be unaccesible).

Did I already mention, that the game will run fast and faster the more enemies you have killed? I never won the game, my best result was approximately 10 surviving hostile ships... but I guarantee that there is program code for the very unlikely event that you will shoot them down all.

If you dont want to load the machine language program with the simple BASIC stub, you can load "SPCASM" as an alternative. This file contains the ML code only:
start (1st occupied byte): $09A6
end (last occupied byte) : $28AE
entry point of code      : $27A0 (:= 10144 dec.)

Saving the program (including BASIC stub):
1) Enter the built in Terminal Interface Monitor (TIM) by SYS1024
2) Load the program .L "SPACE",08
3) Save the program .S "@0:SPACE",08,0401,28AE
4) leave TIM with .X

Without the stub:
1) Enter the built in TIM monitor by SYS1024
2) Load the program .L "SPCASM",08
3) Save the program .S "@0:SPCASM",08,09A6,28AE
4) leave TIM with .X

For those who don't remember - the "@0:" in filename is required if you want to overwrite a file. Without, it won't be saved!