Mars 22, 2010
Memory is as fundamental to computer architecture as any other element. Theability of a systems memory to transact the right quantity of data in the right spanof time has a substantial impact on how that system ful?lls its design goals. Digitalengineers struggle with innovative ways to improve memory density and bandwidthin a way that is tailored to a speci?c applications performance and cost constraints.
Knowledge of prevailing memory technologies strengths and weaknesses is a keyrequirement for designing digital systems. When memory architecture is chosenthat complements the rest of the sys- tem, a successful design moves much closerto fruition. Conversely, inappropriate memory architecture can doom a good ideato the engineering doldrums of impracticality brought on by arti?cial complexity.This chapter provides an introduction to various solid-state memory technologiesand explains how they work from an internal structural perspective as well as aninterface timing perspective.
A memorys internal structure is important to an engineer, because it explains whythat memory might be more suited for one application over another. Interface timingis where the rubber meets the road, because it de?nes how other elements in thesystem can access memory components contents. The wrong interface on amemory chip can make it dif?cult for external logic such as a microprocessorto access that memory and still have time left over to perform the necessaryprocessing on that data. Basic memory organization and terminology are introduced?rst. This is followed by a discussion of the prevailing read-only memorytechnologies: EPROM, ?ash, and EEPROM. Asynchronous SRAM and DRAMtechnologies, the foundations for practically all random-access memories, arepresented next. These asynchronous RAMs are no longer on the forefront ofmemory technology but still ?nd use in many systems. Understanding their operationnot only enables their application, it also contributes to an understanding of themost recent synchronous RAM technologies. (High-per-formance synchronousmemories are discussed later in the book.) The chapter concludes with adiscussion of two types of specialty memories: multiport RAMs and FIFOs.Multiport RAMs and FIFOs are found in many applications where memoryserves less as a storage element and more as a communications channelbetween distinct logic blocks.
Knowledge of prevailing memory technologies strengths and weaknesses is a keyrequirement for designing digital systems. When memory architecture is chosenthat complements the rest of the sys- tem, a successful design moves much closerto fruition. Conversely, inappropriate memory architecture can doom a good ideato the engineering doldrums of impracticality brought on by arti?cial complexity.This chapter provides an introduction to various solid-state memory technologiesand explains how they work from an internal structural perspective as well as aninterface timing perspective.
A memorys internal structure is important to an engineer, because it explains whythat memory might be more suited for one application over another. Interface timingis where the rubber meets the road, because it de?nes how other elements in thesystem can access memory components contents. The wrong interface on amemory chip can make it dif?cult for external logic such as a microprocessorto access that memory and still have time left over to perform the necessaryprocessing on that data. Basic memory organization and terminology are introduced?rst. This is followed by a discussion of the prevailing read-only memorytechnologies: EPROM, ?ash, and EEPROM. Asynchronous SRAM and DRAMtechnologies, the foundations for practically all random-access memories, arepresented next. These asynchronous RAMs are no longer on the forefront ofmemory technology but still ?nd use in many systems. Understanding their operationnot only enables their application, it also contributes to an understanding of themost recent synchronous RAM technologies. (High-per-formance synchronousmemories are discussed later in the book.) The chapter concludes with adiscussion of two types of specialty memories: multiport RAMs and FIFOs.Multiport RAMs and FIFOs are found in many applications where memoryserves less as a storage element and more as a communications channelbetween distinct logic blocks.
afër : E-libër Complete_Digital_Design
