Hardware and Embedded Systems Review

Flashcards cover hardware basics, embedded systems, storage types, memory (SRAM/DRAM/ROM), sensors, actuators, control systems, and peripherals like printers, HDDs, SSDs, opticals, and touchscreens.

What are the three main components of a general-purpose computer system?

Processor, memory, and input/output functionality.

What is primary storage and what is it used for?

The computer’s main memory that stores a set of critical program instructions and data.

What is secondary storage?

Non-volatile storage for noncritical data that will not be frequently accessed.

What is removable secondary storage used for?

File backup/archiving or portable transfer of files to another device.

What is an embedded system?

A small computer inside a larger device that controls the device and allows user interaction; typically one or a few tasks.

What is a microcontroller?

An embedded system integrated circuit with built-in memory.

Name three common examples of embedded systems.

Central heating systems, engine management systems in vehicles, and domestic appliances (dishwashers, TVs, digital phones).

Why are embedded devices usually not programmable by the user?

Programming is typically done beforehand by the manufacturer; upgrades may be possible by connecting to a PC.

What are the three components of an embedded system as listed?

Hardware, Application Software, Real Time Operating System (RTOS).

What are two major advantages of embedded systems?

Small size and relatively low cost.

What is a key reliability factor for embedded systems due to manufacturing?

Mass production leads to reliability.

What is a major challenge in upgrading embedded systems?

Difficult to upgrade to take advantage of new technology.

Why can troubleshooting embedded devices be challenging?

Faults in the device require specialist knowledge.

What is latency in the context of hard disks?

The time it takes for a specific block of data on a track to rotate into position at the read-write head.

What is fragmentation and how is it mitigated?

Sectors become scattered over the disk; defragmentation tidies up sectors to improve performance.

What are the main benefits of SSDs over HDDs?

No moving parts (more reliable), lighter, faster data access, lower power consumption, cooler, thinner.

What is NAND memory and where is it commonly used?

NAND flash memory; used in solid-state storage like SSDs; stores data as 0s and 1s in transistors.

What is NOR memory and how does it differ from NAND?

NOR memory (EEPROM-like) allows byte-level read/erase and is faster for small accesses but more expensive.

What is ROM used for in PCs and embedded systems?

Non-volatile storage for boot code and firmware.

What is RAM and why is it volatile?

Random Access Memory; stores currently executing programs; contents are lost when power is off.

What is SRAM?

Static RAM; uses six-transistor cells; fast, does not require refreshing, more expensive; used for CPU cache.

What is DRAM?

Dynamic RAM; uses a capacitor and a transistor; requires refreshing; cheaper and higher density; main memory.

What is the difference between PROM, EPROM, and EEPROM?

PROM is programmable once; EPROM is erasable with ultraviolet light; EEPROM is erasable electronically (byte-level in many cases).

What is a buffer?

Temporary RAM storage to smooth speed differences between a processor and a peripheral (e.g., printer).

What is the Von Neumann architecture?

Memory stores both program instructions and data; the CPU fetches instructions and data from the same memory.

What is a sensor in a control system?

An input device that detects a physical property (e.g., temperature, pressure) and outputs a signal.

What is an actuator?

A device that converts electrical energy into mechanical movement to drive equipment.

What is feedback in a control system?

A loop where output data is fed back through sensors to adjust future actions.

What is the difference between monitoring and control systems?

Monitoring observes, without altering the environment; control systems act to change the state based on measurements.

What is an event-driven control system?

A controller that acts in response to an event detected by sensors (e.g., part presence, level sensors).

What is a time-driven control system?

A controller that acts at specific times or after certain time intervals (e.g., shift bells, painting cycles).

What are the common steps in process control?

Measure sensor inputs, process data with software, decide action, actuate devices.

What is a sensor?

An input device that detects a physical property and outputs an electrical signal (e.g., thermocouple).

What is an actuator's role in process control?

To drive mechanical devices (valves, motors) based on software output.

What is a virtual reality headset?

An output device worn on the head providing stereo sound, head-tracking sensors, and per-eye images for VR.

What is a touchscreen and what are the two main technologies?

A display that is both input and output; resistive and capacitive technologies.

How does a resistive touchscreen detect touch?

Two conductive layers contact when pressed; coordinates are calculated from changes in the electric field.

How does a capacitive touchscreen detect touch?

Touch transfers charge at the touch point; processor computes coordinates from corner charge differences.

What is the basic principle of a laser printer?

A laser creates a latent image on a charged drum; toner sticks to exposed areas and is transferred to paper and fused with heat.

How does a 3D printer build objects?

Layer by layer using a CAD blueprint or 3D scan; deposits material and fuses layers with adhesive or UV light.

What is hard-disk latency and why does it matter?

Time for a data block to rotate into position; affects wait times and performance.

What is defragmentation in a hard disk?

Reorganizing data to reduce fragmentation and improve sequential access performance.

What is the role of optical disks (CD/DVD) and how is data read?

Data is stored as pits and lands on a spiral track; a red laser reads/writes data; discs can be R or RW; DVD uses dual layers to increase capacity.

What is the difference between SSDs and HDDs in terms of cost and reliability?

SSDs are more reliable and faster with no moving parts but generally more expensive per GB than HDDs.

What is buffering in printers or I/O devices?

Temporary memory to absorb speed differences between CPU and peripheral during I/O operations.

What is the difference between volatile and non-volatile memory?

Volatile memory (e.g., RAM) loses data when power is off; non-volatile memory (e.g., ROM, flash) retains data.

What is RAM used for in a computer?

Storing currently executing programs and data that the CPU needs immediately.

What is ROM used for in embedded systems?

Storing boot code or firmware that does not change during normal operation.