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⏱️ Time Model and Cycles
1. Overview
PROMETEU is a time-oriented system.
Nothing happens "instantly".
Every action consumes measurable time, expressed in execution cycles.
This chapter defines:
- the system's base clock
- the concept of a PROMETEU cycle
- how time is distributed across frames
- how the CAP (Execution Cap) relates to this model
2. System Base Clock
PROMETEU operates with a fixed clock of 60 Hz.
This means:
- 60 iterations of the main loop per second
- each iteration corresponds to one frame
- the clock is deterministic and stable, regardless of the platform
The clock defines the machine's rhythm, not the amount of mandatory work per frame.
3. The PROMETEU Frame
A PROMETEU frame represents a complete unit of execution.
Each frame conceptually executes the following stages:
FRAME N
──────────────
INPUT
UPDATE
DRAW
AUDIO
SYNC
──────────────
The system guarantees:
- fixed order
- predictable repetition
- absence of "ghost" frames
4. PROMETEU Cycles
4.1 Definition
A PROMETEU cycle is the smallest abstract unit of time in the system.
- each VM instruction consumes a fixed number of cycles
- peripheral calls also have a cost
- the cost is documented and stable
Cycles are:
- countable
- comparable
- independent of real hardware
4.2 Why cycles, and not milliseconds?
PROMETEU does not measure time in milliseconds because:
- milliseconds vary between platforms
- real clocks differ
- jitter and latency hide the real cost
Cycles allow stating:
"This program is more expensive than that one,
regardless of where it runs."
5. Per-Frame Budget
Each frame has a maximum cycle budget.
This budget:
- is reset every frame
- does not accumulate unused cycles
- represents the capacity of the "virtual CPU"
Conceptual example
Frame Budget:10,000cycles
Used:
-Update logic:4,200
-Draw calls:3,100
-Audio:900
Remaining:
1,800cycles
6. Separation between Clock and Work
PROMETEU does not require all logic to run every frame.
The programmer is explicitly encouraged to distribute work over time.
Common examples
- enemy logic every 2 frames (30 Hz)
- pathfinding every 4 frames (15 Hz)
- animations independent of AI
- timers based on frame count
This reflects real-world practices from:
- classic consoles
- embedded systems
- microcontroller firmware
Not everything needs to happen now.
7. Temporal Distribution as Architecture
PROMETEU treats work distribution over time as an architectural decision.
This means that:
- code that runs every frame is more expensive
- distributed code is more efficient
- optimization is, first and foremost, temporal organization
PROMETEU teaches:
performance doesn't just come from "less code",
but from when the code runs.
8. Execution CAP (Contextual Budget)
8.1 What is the CAP
The CAP defines a set of technical limits associated with a specific context, such as:
- Game Jams
- academic evaluations
- technical challenges
The CAP can define:
- maximum cycle budget per frame
- memory limit
- peripheral call limits
8.2 CAP does not block execution
Fundamental rules:
- the game always runs
- the game can always be packaged
- the game can always be played
The CAP never prevents execution.
8.3 CAP generates evidence, not punishment
When a CAP is active, PROMETEU:
- measures execution
- records peaks
- identifies bottlenecks
- generates a certification report
This report:
- does not block the game
- does not invalidate the delivery
- documents compliance or non-compliance
9. Time-Based Certification
PROMETEU certification analyzes:
- average cycle usage per frame
- maximum peaks
- problematic frames
- cost distribution
Example:
Target CAP:PROMETEU-LITE
Frame Budget:5,000cycles
Frame 18231:
Used:5,612cycles❌
Primary cause:
enemy.updateAI():1,012cycles
This certification accompanies the game as a technical artifact.
10. Pedagogical Implications
The time and cycles model allows teaching:
- execution planning
- time-oriented architecture
- technical trade-offs
- reading real profiles