In computer graphics hardware, how can a basic ('dumb') digitizer or graphics tablet be upgraded to a 'smart' device with on-board capabilities such as coordinate processing and device control?

Introduction / Context:
Digitizers (graphics tablets and related input surfaces) convert pen or puck movement into coordinate data. Early or basic units are often called 'dumb' because they output raw, minimally processed signals and rely on the host computer for decoding. This question asks what addition transforms such a device into a 'smart' peripheral capable of local processing and richer features.

Given Data / Assumptions:

• 'Dumb' denotes minimal on-device logic and no independent control.
• 'Smart' implies local processing, buffering, and protocol handling.
• We are considering typical peripheral electronics used in HCI and CAD/CAM setups.

Concept / Approach:
The key to 'smartening' a peripheral is embedding computation close to the sensor. A microprocessor or microcontroller can sample the analog front end, filter and linearize signals, handle calibration, compress or packetize coordinates, and implement communication protocols (USB, serial, Bluetooth). This reduces latency and offloads work from the host, enabling features such as pressure curves, button mappings, and firmware updates.

Step-by-Step Solution:
1) Identify the limitation of a dumb digitizer: raw, unprocessed output. 2) Determine what component enables local decision making: a microprocessor. 3) Evaluate alternatives: coupling, keyboard, scanner do not provide onboard computation for the digitizer's signals. 4) Conclude that embedding a microprocessor is the defining upgrade.

Verification / Alternative check:
Smart input devices across domains (mice, keyboards, game controllers) all incorporate microcontrollers to perform scanning, debouncing, filtering, and protocol management before sending concise data to the host.

Why Other Options Are Wrong:
Option B: Electromagnetic coupling refers to sensing or power transfer, not local intelligence.
Option C: A keyboard is a different input device, not an upgrade path for digitizers.
Option D: A scanner captures images; it does not process tablet coordinates.
Option E: Incorrect because a microprocessor is precisely what adds smart capability.

Common Pitfalls:
Confusing sensing technology (how positions are detected) with processing (how signals are interpreted). The sensor can remain unchanged; adding a microprocessor changes capability.

Final Answer:
A microprocessor