tailieunhanh - Bài giảng Computer Organization and Architecture: Chapter 5

Mời các bạn cùng tìm hiểu Semiconductor Memory; Semiconductor Memory Types; Memory Cell Operation;. được trình bày cụ thể trong "Bài giảng Computer Organization and Architecture: Chapter 5 - Internal Memory". | William Stallings Computer Organization and Architecture 6th Edition Chapter 5 Internal Memory Semiconductor Memory Types Semiconductor Memory RAM Misnamed as all semiconductor memory is random access Read/Write Volatile Temporary storage Static or dynamic Memory Cell Operation Dynamic RAM Bits stored as charge in capacitors Charges leak Need refreshing even when powered Simpler construction Smaller per bit Less expensive Need refresh circuits Slower Main memory Essentially analogue Level of charge determines value Dynamic RAM Structure DRAM Operation Address line active when bit read or written Transistor switch closed (current flows) Write Voltage to bit line High for 1 low for 0 Then signal address line Transfers charge to capacitor Read Address line selected transistor turns on Charge from capacitor fed via bit line to sense amplifier Compares with reference value to determine 0 or 1 Capacitor charge must be restored Static RAM Bits stored as on/off switches No . | William Stallings Computer Organization and Architecture 6th Edition Chapter 5 Internal Memory Semiconductor Memory Types Semiconductor Memory RAM Misnamed as all semiconductor memory is random access Read/Write Volatile Temporary storage Static or dynamic Memory Cell Operation Dynamic RAM Bits stored as charge in capacitors Charges leak Need refreshing even when powered Simpler construction Smaller per bit Less expensive Need refresh circuits Slower Main memory Essentially analogue Level of charge determines value Dynamic RAM Structure DRAM Operation Address line active when bit read or written Transistor switch closed (current flows) Write Voltage to bit line High for 1 low for 0 Then signal address line Transfers charge to capacitor Read Address line selected transistor turns on Charge from capacitor fed via bit line to sense amplifier Compares with reference value to determine 0 or 1 Capacitor charge must be restored Static RAM Bits stored as on/off switches No charges to leak No refreshing needed when powered More complex construction Larger per bit More expensive Does not need refresh circuits Faster Cache Digital Uses flip-flops Stating RAM Structure Static RAM Operation Transistor arrangement gives stable logic state State 1 C1 high, C2 low T1 T4 off, T2 T3 on State 0 C2 high, C1 low T2 T3 off, T1 T4 on Address line transistors T5 T6 is switch Write – apply value to B & compliment to B Read – value is on line B SRAM v DRAM Both volatile Power needed to preserve data Dynamic cell Simpler to build, smaller More dense Less expensive Needs refresh Larger memory units Static Faster Cache Read Only Memory (ROM) Permanent storage Nonvolatile Microprogramming (see later) Library subroutines Systems programs (BIOS) Function tables Types of ROM Written during manufacture Very expensive for small runs Programmable (once) PROM Needs special equipment to program Read “mostly” Erasable Programmable (EPROM) Erased by UV Electrically Erasable (EEPROM)

• Hệ điều hành
• Bài giảng Computer Organization and Architecture
• Computer Organization and Architecture
• Bộ nhớ trong
• Bộ nhớ bán dẫn
• Semiconductor Memory Types
• Memory Cell Operation