The Synthesis: Combining All 68 Lessons
This final project demonstrates how to structure and link together all the advanced modules developed in this series (Interrupts, Graphics, I/O, and Logic) to create a working, real-time application.
The Engine’s Goal: Display a sprite that moves smoothly in response to keyboard input, accelerates due to gravity, and stops when hitting a floor tile.
Engine Initialization (The Setup Phase)
This phase runs only once, at boot, and relies heavily on your OS and peripheral posts (Parts 52, 62).
The Setup Sequence:
INIT_SYSTEM:
DI ; Disable Interrupts (Part 48)
LD SP, STACK_TOP ; Initialize Stack (Part 52)
CALL INIT_MEMORY_BANKS ; Configure RAM/ROM (Part 43)
CALL INIT_VIDEO ; Clear screen (Part 21)
CALL INIT_CTC_TIMER ; Set up VSync Timer Interrupt (Part 62)
CALL INIT_SPRITE_DATA ; Set initial X, Y, and velocity (Part 31)
IM 2 ; Set Interrupt Mode 2 (Part 60)
EI ; Enable Interrupts (Part 48)
RET
The Main Game Loop Structure
The main loop runs infinitely, synchronizing all actions to the V-Blank Interrupt (VBI) for smooth animation (Part 25).
GAME_MAIN_LOOP:
CALL CHECK_KEYBOARD ; Check the FIFO buffer (Part 58)
CALL UPDATE_LOGIC ; Apply physics/gravity (Part 34)
HALT ; Wait for the next VBI interrupt (Part 25)
CALL RENDER_SPRITES ; Draw/erase sprites (Part 32)
JP GAME_MAIN_LOOP ; Loop infinitely
The VBI Interrupt Service Routine (The Scheduler)
The VBI is the real heart of the game, forcing the execution of critical physics and rendering updates.
The ISR (Simplified):
VBI_ISR_HANDLER:
PUSH AF, HL ; Save necessary context (Part 47)
CALL PHYSICS_ROUTINE ; Updates sprite velocity/position
CALL COLLISION_ROUTINE ; Check if the new position is solid (Part 37)
CALL RESOLUTION_ROUTINE; If collision, backtrack/stop (Part 35)
POP HL, AF
RETI ; Return from Interrupt (Part 48)
Final Conclusion
This engine represents the fusion of the entire curriculum:
- Low-Level Control from I/O ports and interrupt vectors.
- Data Structures from the sprite descriptors and linked lists.
- Algorithms from the multiplication, shifts, and physics routines.
Congratulations on completing the most comprehensive Z80 Assembly curriculum!