24 NVM 10

24 NVM 10 - Non-volatile Memory This lecture covers various...

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NVM retains data without power supplied. Most “non-volatile” data storage is still accomplished using magnetic disks. Semiconductor NVM promises compact, low power, rugged storage. Non-volatile Memory This lecture covers various representative types of non- volatile memory including advanced types…
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System solution requirements Logic core CMOS 6LM Cache SRAM CMOS 2LM Microcode/data NVM (Flash) Mass memory/operating DRAM Is there scope for any other memory types ? NVM in the form of “Flash memory” is also used as content storage media for digital cameras, MP3 music players, etc. Solid state memory in computer systems typically involves multiple technologies…
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NVM Basic Types Read Only Memory (ROM) Programmable ROM (PROM) Erasable Programmable ROM (EPROM) Electrically Erasable PROM (E 2 PROM) HDD is still used for mass storage as it has the lowest cost per bit but solid state drives (SSDs) are slowly taking
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Memory chip layout Cell array #1 partition into blocks Sense amps , read/write Array #2 Few I/O, multiplex access High speed bus
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Mask programmable ROM - Committed during processing using mask patterns - Diode or transistor arrays Build array of diodes but only connect some ROM Column Row No Connection Why diodes? (why not just make wires?) How would we do this?
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Transistor ROM (bipolar and MOS) is more common than just diodes Easier to make and integrate into circuit Can program data during processing by - Implant into channel to change V T in some devices so that they only turn on at logic 1 input level (e.g. 5 V) - Or leave gate off in some Transistor ROM
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ROM Cell Arrays Data Out V DD Pull-ups C 1 C 2 R 2 R 1 Data Out V DD C 1 C 2 R 2 R 1 NOR Array NAND Array Implant to lower V T Could other types of memory be arranged like this?
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Fuse PROM V CC V CC V CC V CC NiCr fuses fabricated in metallization Blown using high current pulse “Old” technology but still exists in legacy systems Is this a low power technology?
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24 NVM 10 - Non-volatile Memory This lecture covers various...

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