QUAID! Drone Défense System 

By Joe Powton    ©2022

BACKGROUND
==========

      I bought my Aquarius in 1983 and spent many nights writing programs for it as commercial software was scarce.
      Always frustrated by the slow speed of the BASIC and limited memory, I wished to write MACHINE CODE software like the professionals. Back in the day I didn’t have the access to the necessary information, so it all remained a mystery.
      Nearly 40 years later I decided to give Z80 code a go and this program is my first attempt, so don’t judge.

GAME
====
      A drone defence tower protects your city from attack. It’s developed a fault and cannot see the altitude of the enemy attackers. Your help is needed to select the correct height and therefore destroy the missiles of death.
      Don’t miss as the Power Reserve is affected.

VERSIONS
========
      The original version is for the unexpanded Aquarius and loads in two parts. The first loads the machine code and the second contains the game code.
      A second version for the 16K expanded contains everything in one program and some graphic enhancements.

MACHINE CODE
============
      Four subroutines have been written. 
         1) Paints the entire screen the same colour as 13312.
         2) Paints the central section. (Reused in the Game Over Sequence)
         3) Beam. Called to paint and clear the beam.
         4) Plane routine. 

      Written for fun. No warranty. 
      Yes, it could be improved, but this is as far as I’m going to take it for now. 


Joe
11/Nov/2022



