# PFES-ENG-010 — Firmware Services

**Status:** Active  
**Knowledge Cycle Stages:** Observe, Understand

## Purpose

Identify reusable routines and service subsystems that support many firmware capabilities.

## Engineering Problem

Without recognizing common services, engineers repeatedly reverse engineer memory functions, timing, flash access, sense builders, queues, and hardware abstraction.

## Historical Engineering Evolution

Older reports already searched for memcpy, memset, memcmp, delay, flash write/erase, sense-data construction, and command services. This demonstrated that service identification is an engineering map, not mere function naming.

## Engineering Discoveries

- Services are stable landmarks across revisions.
- Services reveal dependency structure.

## Architectural Decisions

- Record confidence and supporting patterns.
- Do not conflate compiler idioms with validated service identity.

## Knowledge Produced

- Service inventories
- Reusable labels
- Dependency edges

## Knowledge Consumed

- Topology
- Representations
- Evidence

## Current Engineering State

Current service work includes memory routines, delays, flash programming, sense builders, command support, timers, and diagnostics.

## Engineering Lessons

- Recognizing services accelerates every later subsystem analysis.

## Negative Knowledge

Project Frankenstein no longer assumes:

- Every routine is unique.
- A guessed function name is equivalent to validated identity.

## Current Implementations

- Stage 5B heuristics
- Manual disassembly
- Cross-family matching

## Future Implementations

- Service fingerprints
- Genealogy
- Architecture-independent service models

## Open Questions

To be expanded during engineering review.

## Why This Chapter Exists

Capabilities are built from services; engineers need those reusable landmarks.
