Unit6-MemoryCells-Nazarian-EE577B-Fall10

Unit6-MemoryCells-Nazarian-EE577B-Fall10 - University...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
University of Southern California Viterbi School of Engineering EE577B LSI System Design VLSI System Design igital Memory Cells Digital Memory Cells Shahin Nazarian Fall 2010
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Introduction In general the number of transistors for data storage is much larger than that for logic operations and other purposes Maximum realizable data storage capacity doubles every two years The area efficiency , i.e., the number of stored data bits per nit area is one of the key design criteria that determine the unit area is one of the key design criteria that determine the overall storage capacity and hence the memory cost per bit Another key parameter, is the memory access time , i.e., the ime required t st re and/ r retrieve a particular data bit in time required to store and/or retrieve a particular data bit in the memory. It specifies the memory speed Static and dynamic power consumption of memory is also a significant factor to be considered during design The semiconductor memory is generally classified according the type of data storage and data access, e.g., R/W memory must Shahin Nazarian/EE577B/Fall 2010 permit modification (writing) of data bits stored in memory array as well as their retrieval (reading) 2
Background image of page 2
Digital Memories Types Memory Arrays Random Access Memory Serial Access Memory Content Addressable Memory (CAM) Read/Write Memory (RAM) Read Only Memory (ROM) Shift Registers Queues * (Volatile) (Nonvolatile) Static RAM RAM) Dynamic RAM RAM) First In First Out IFO) Last In First Out IFO) Serial In Parallel Out IPO) Parallel In Serial Out ISO) (SRAM) (DRAM) (FIFO) (LIFO) (SIPO) (PISO) Mask ROM Programmable ROM (PROM) Erasable Programmable ROM (EPROM) Electrically Erasable Programmable ROM EPROM) Flash ROM Shahin Nazarian/EE577B/Fall 2010 3 * CAM has applications in cache tag matching where the whole thing is searched for a tag (EEPROM)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Random Access Technology As the technology evolves randomness plays more important role and we want data to be randomly accessible e also want the access time to not be a function of the We also want the access time to not be a function of the location of the memory data Memory can be classified into Random Access Memory (RAM) and non-RAM memories Random Access Memories can be further classified into ROMs and Read/Write (R/W) memories In RAM technology access time is the same regardless of the location of the memory data R/W memory is also commonly called RAM due to historical reasons R/W (or RAMs) have two main types of Dynamic RAMs Shahin Nazarian/EE577B/Fall 2010 (DRAMs) and Static RAMs (SRAMs) 4
Background image of page 4
Not-so-Random Access Technology Random Access: DRAM : Dynamic Random Access Memory High density, low power, cheap, slow Dynamic: need to be “refreshed” regularly SRAM : Static Random Access Memory Low density, high power, expensive, fast Static: content will last “forever”(until lose power) t nd m” A T h n l : Not-so-rando m±Access Technology: Access time varies from location to location and from time to time It’s random accessible, but it’s not the same time Examples: Disk, CDROM Shahin Nazarian/EE577B/Fall 2010 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 48

Unit6-MemoryCells-Nazarian-EE577B-Fall10 - University...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online