Hardware (2)

BUFFER

A buffer is a temporary storage area in memory (RAM) used to hold data while it is being transferred between two devices or processes that operate at different speeds.
Analogy: A buffer is like a queue at a supermarket checkout. Customers (data) arrive faster than the cashier (slow device) can serve them. The queue (buffer) holds customers until the cashier is ready.

Printer Buffer

Aspect	Description
Problem	Printer is slow; CPU is fast
Solution	Print job is sent to a printer buffer
Operation	CPU sends entire document to buffer quickly; printer reads from buffer slowly
Benefit	CPU can continue other work while printer prints

Video Streaming Buffer

Aspect	Description
Problem	Network speed varies; video must play smoothly
Solution	Video data is pre-loaded into a buffer
Operation	Buffer stores several seconds of video before playback begins
Benefit	Prevents buffering/stuttering if network speed drops

Benefits of a buffer

Speed matching	Allows fast and slow devices to work together efficiently
No data loss	Prevents data loss when fast device outpaces slow device
CPU efficiency	CPU can continue working while I/O device catches up
Smooth playback	Prevents buffering/stuttering in streaming media
Batch processing	Allows data to be collected and processed in batches

Drawbacks of a buffer

Drawback	Explanation
Memory usage	Requires additional RAM for temporary storage
Latency	Adds slight delay (data must be stored before processing)
Buffer overflow	If buffer fills up, data may be lost
Buffer underrun	If buffer empties, slow device may stall

ROM AND RAM

Feature	RAM	ROM
Volatility	Volatile — data lost when power is removed	Non-volatile — data retained when power is removed
Read/Write	Read and Write — data can be read from and written to	Read Only — data cannot normally be modified
Purpose	Stores active programs and data currently in use	Stores boot-up instructions (BIOS/UEFI)
Speed	Faster than ROM	Slower than RAM
Capacity	Larger (GBs: 4GB – 128GB)	Smaller (MBs: 2MB – 64MB)
Cost	More expensive per GB	Cheaper per GB
Contents	Changes constantly as programs run	Fixed at time of manufacture
Location	Main memory (system memory)	Main memory (usually on motherboard)
Usage	OS, applications, user data	System startup, firmware, bootstrap loader
Type	Dynamic (DRAM) or Static (SRAM)	Mask ROM, PROM, EPROM, EEPROM

Types of RAM:

Type	Description
DRAM (Dynamic RAM)	Needs to be refreshed thousands of times per second; slower but cheaper; used for main memory Consists of transistors and capacitors Higher memory Consumes more power than SRAM
SRAM (Static RAM)	Does not need refreshing; faster but more expensive; used for cache memory make use of flip-flops. Can use more power than DRAM when used frequently

Types of ROM:

Type	Description
Mask ROM	Permanently programmed during manufacture; cannot be changed at all
PROM (Programmable ROM)	Can be programmed once by the user (with special hardware)
EPROM (Erasable PROM)	Can be erased with UV light and reprogrammed
EEPROM (Electrically Erasable PROM)	Can be erased and reprogrammed electronically (used for BIOS updates)

Monitoring VS Control System.

System	Definition
Monitoring System	A system that measures and records data from the environment without taking any automatic action to change it
Control System	A system that measures data from the environment and automatically takes action to change or maintain it based on the readings

Aspect	Monitoring System	Control System
Purpose	Observes and records data	Observes AND acts based on data
Action	No automatic action taken	Automatic action taken to maintain/change conditions
Output	Data displayed or logged (e.g., screen, file)	Physical action (e.g., motor, heater, valve)
Feedback loop	No feedback loop	Has a feedback loop
Human involvement	Human must interpret data and decide action	System acts automatically without human intervention