Early MemoriesEarly MemoriesEarly MemoriesEarly MemoriesModern Memory ChoicesROMsEPROMsEEPROM and FLASHStatic RAM CellStandard SRAM: 6264Standard SRAM: 6264Standard SRAM: 6264Toshiba TC55V16256J 256K $ imes $ 16Toshiba TC55V16256J 256K $ imes $ 16Dynamic RAM CellAncient DRAM: 4164Basic DRAM read and write cyclesPage mode read cycleSamsung 8M $ imes $ 16 SDRAMSamsung 8M $ imes $ 16 SDRAMSDRAM: Control SignalsSDRAM: Timing with 2-word burstsMemoryProf. Stephen A. [email protected] UniversitySpring 2007Memory – p. 1/??Early MemoriesWilliams Tube CRT-based random accessmemory, 1946. Used on the Manchester Mark I.2048 bits.Memory – p. 2/??Early MemoriesMercury acousticdelay line.Used in the EDASC,1947.32 × 17 bitsMemory – p. 3/??Early MemoriesMagnetic core memory, 1952. IBM.Memory – p. 4/??Early MemoriesMagnetic drum memory. 1950s & 60s.Secondary storage.Memory – p. 5/??Modern Memory ChoicesFamily Programmed PersistenceMask ROM at fabrication ∞PROM once ∞EPROM 1000s, UV 10 yearsFLASH 1000s, block 10 yearsEEPROM 1000s, byte 10 yearsNVRAM ∞ 5 yearsSRAM ∞ while poweredDRAM ∞ 64 msMemory – p. 6/??ROMsMemory – p. 7/??EPROMsMemory – p. 8/??EEPROM and FLASHSourceDrain(bit line)ChannelWord Linefloating gateOxideSlow writeFowler-NordheimTunnelingEEPROM: bitat a timeFLASH: blockat a timeSource: SSTMemory – p. 9/??Static RAM CellWordBitBitMemory – p. 10/??Standard SRAM: 6264CS226CS120WE27OE22Addr[12:0]10–2,25–23,21D[7:0]19–15,13–118K × 8Can be very fast:Cypress sells a 55nsversionSimple, asynchronousinterfaceMemory – p. 11/??Standard SRAM: 6264HHHLLLLLHHHLLLLLHHHCS1LLLHHHHHLLLHHHHHLLLCS2HHHHLLLHHHHHHHHHHHHHHHHWEHHHHHHHHHHHHHHHHHLLHHHHOEUUVVVVVVVUUUVVVVUUUAddrZZVVVVVVVV ZZZZVV ZZZDataMemory – p. 12/??Standard SRAM: 6264CY6264-1A1A2A3A4A5A6A7A8I/O0256 x 32 x 8ARRAYINPUT BUFFERCOLUMN DECODERPOWERDOWNI/O1I/O2I/O3I/O4I/O5I/O6I/O7CE1CE2WEOEMemory – p. 13/??Toshiba TC55V16256J 256K × 16CE6WE17OE41LB39UB40Addr[17:0]23,22,18–21,24–27,42–44,1–5D[15:0]38–35,32–29,16–13,10–712 or 15 ns access timeAsynchronous interfaceUB, LB select bytesMemory – p. 14/??Toshiba TC55V16256J 256K × 16Memory – p. 15/??Dynamic RAM CellRowColumnBasic problem: LeakageSolution: RefreshMemory – p. 16/??Ancient DRAM: 416464K × 1Apple IIe vintageRAS4CAS15WE3DIN2DOUT14Addr[7:0]9,13,10–12,6,7,5Memory – p. 17/??Basic DRAM read and write cyclesHHLLLLLLLLLHHLLLLLLHHRASHHHHHHLLLLLHHHHHHLLHHCASVVVVUUUUUVVVVUUUUAddrFFFFÆHHFFFFFFFFFFLLFFFWEUUUUUUUUUUUUUUUUUUUUVVUUUDinZZZZZZZZVVV ZZZZZZZZZZZZZZDoutRowColRowColMemory – p. 18/??Page mode read cycleHHLLLLLLLLLLLLLLLLLLLLLLHRASHHHHHHLLLHLLLHLLHCASVVVVUUUVVUVVUUUAddrFFFFÆHHHFÆHHHÆHHHHFFWEUUUUUUUUUUUUUUUUUUUUUUUUUUUUUDinZZZZZZZZVVV ZVVV ZVVVDoutRowCol Col ColMemory – p. 19/??Samsung 8M × 16 SDRAMCLK38CKE37RAS15CAS15WE3LDQM15UDQM39DQ[15:0]Addr[11:0]BA[1:0]21,20Bank addressAddress (multiplexed)Data I/OUpper byte enableLower byte enableWrite enableColumn Address StrobeRow Address StrobeClock EnableClockSynchronous interfaceDesigned for burst-mode operationFour separate banks; pipelined operationMemory – p. 20/??Samsung 8M × 16 SDRAMBank SelectData Input Register8M x 4 / 4M x 8 / 2M x 168M x 4 / 4M x 8 / 2M x 16Sense AMPOutput BufferI/O ControlColumn DecoderLatency & Burst LengthProgramming RegisterAddress RegisterRow BufferRefresh CounterRow Decoder Col. BufferLRASLCBRLCKELRAS LCBR LWE LDQMCLK CKE CSRAS CAS WE L(U)DQMLWELDQMDQiCLKADDLCAS LWCBR8M x 4 / 4M x 8 / 2M x 168M x 4 / 4M x 8 / 2M x 16Timing RegisterMemory – p. 21/??SDRAM: Control SignalsRAS CAS WE action1 1 1 NOP0 0 0 Load mode register0 1 1 Active (select row)1 0 1 Read (select column, start burst)1 0 0 Write (select column, start burst)1 1 0 Terminate Burst0 1 0 Precharge (deselect row)0 0 1 Auto RefreshMode register: selects 1/2/4/8-word bursts, CASlatency, burst on writeMemory – p. 22/??SDRAM: Timing with 2-word burstsL ClkHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHRASHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCASHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHWEUUUUUUUUUUUUUUUUUUUUUUUUUUUUUAddrUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUBAZZZZZZZZZZZZZZZZ ZZZZZZZZ ZZZZZDQOpRBCBCBW W R RLoad Active Write ReadRefreshMemory – p.
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