Ink-jet printers

• Non-impact printer
• Inexpensive home printer
• Color output common using CMYK
• Cyan, magenta, yellow, black
• Sprays ink onto paper
• Speed measured in pages per minute
• Quality expressed as dots per

Laser printer

– Non-impact printer

– Produces high quality documents

– Color or black and white

– Print process

• Laser draws text on page

• Toner sticks to text

• Toner melted to page

– Speed measured in pages per minute

– Quality expressed as dots per inch

Definition of memory and its classification

Memory Hierarchies

Definition of memory and its

classification

Ø Memory

• When you launch a program, it is loaded into and run from memory

Ø Classification of Memory

Ø Internal Processor Memory

Ø Main Memory:

Example: RAM, ROM.

Ø Secondary Memory:

Example: CD, Floppy etc.

Memory Capacity

ü Bit

ü Byte: 1 byte= 8 bits

ü Kilobyte (K or KB): 1KB=1024 bytes

ü Megabyte (M or MB): 1MB=1048579 bytes

ü Gigabyte (G or GB): 1GB=1048876 byte

ü Terabyte

Memory Hierarchies

General Properties of Memory Devices

• Access Time: The average time required to read a fixed amount of information from the memory

• Cycle time: The minimum time between two consecutive memory access operations is called the cycle time.

• Data Transfer rate: The maximum amount of information that can be transferred to or from the memory every second is called the data transfer rate.

Differences between SRAM and DRAM

SRAM	DRAM
High speed RAM	Relatively slower
SRAM is costly	Less costly
Does not require refreshing	Requires refreshing periodically
Generally used for cache	Used for main memory

Difference between RAM & ROM

RAM	ROM
Random Access Memory	Read Only memory
User can read & write into it	User can only read from it
For any type of processing, user must store program & data into RAM	Manufacturer stores instruction into ROM permanently
Temporary or volatile memory	Permanent or non-volatile memory

Cache Memory or High Speed Buffer

Cache Memory

• Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU.

• Cache is located directly on the CPU or between the CPU and RAM, making it faster than normal RAM.

• CPU-resident cache is called Level-1 (L1) cache. External cache is called Level-2 (L2) cache.

• The amount of cache memory has a tremendous impact on the computer's speed.