Post on 24-Dec-2015
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Memory BasicsChapter 8
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RAM Random access memory
ROM Read-only memory
Memory definitions
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RAM
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Control inputs to a memory chip
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Static RAM (SRAM) Consists of internal latches that store the
binary information Dynamic RAM (DRAM)
Stores the binary information in the form of electric charges on capacitors
Properties of memory
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若 Bit select為 1，則接通 1, 2 gates。為1，寫入資料， 3, 4接通。Data in之後產生 B, ，再選word，選到的 5,6,7,8接通，此時不是 Set就是Reset，傳入C或。在Read logic S, R其一為 1，經 2輸出。
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16-word by 1-bit RAM chip
IN
EN
OUT
Three-state buffer
EN IN OUT
0 X Hi-Z
1 0 0
1 1 1
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16x1 RAM using a4x4 RAM cell array
Reduce number of1. Decoder gates2. Inputs per gate3. RAM cells per slice
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8x2 RAM using a4x4 RAM cell array
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A 32K x 8 RAM 32K x 8=215*23=218
Each column 29
Example
9-29
decoder
6-26
decoder
215
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64K x 8 RAM
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256K x 8 RAM
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64K x 16 RAM