Memorias

Memory
CSEE W4840
Prof. Stephen A. Edwards Columbia University

Memory – p. 1/

Early Memories

Williams Tube CRT-based random access memory, 1946. Used on the Manchester Mark I. 2048 bits.Memory – p. 2/

Early Memories

Mercury acoustic delay line. Used in the EDASC, 1947. 32 × 17 bits

Memory – p. 3/

Early Memories

Magnetic core memory, 1952. IBM.

Memory – p. 4/Early Memories

Magnetic drum memory. 1950s & 60s. Secondary storage.

Memory – p. 5/

Modern Memory Choices
Family Programmed Persistence
∞ ∞

Mask ROM at fabrication PROM EPROM FLASHEEPROM NVRAM SRAM DRAM once 1000s, UV 1000s, block 1000s, byte
∞ ∞ ∞

10 years 10 years 10 years 5 years while powered 64 ms

Memory – p. 6/

ROMs

Memory – p. 7/

EPROMs

Memory – p. 8/EEPROM and FLASH
Slow write Oxide FowlerNordheim Tunneling EEPROM: bit at a time FLASH: block at a time
Source: SST

floating gate Word Line Drain Channel (bit line)

Source

Memory – p. 9/Static RAM Cell
Word

Bit

Bit

Memory – p. 10/

Standard SRAM: 6264
19–15,13–11 D[7:0] 10–2,25–23,21 22 27 20 26

Addr[12:0] OE WE CS1 CS2

8K × 8 Can be very fast: Cypress sellsa 55ns version Simple, asynchronous interface

Memory – p. 11/

OE

WE

CS2

CS1

Addr

Standard SRAM: 6264

Data
¢     ¡   ¢     ¡       ¡             ¡   ¡   ¡   ¡   ¡   ¡   ¡    ¡           ¡       ¡   ¢     ¡   ¢     ¢     ¢     ¡     ¡   ¡   ¡ ¡     ¡     ¡       ¢     ¡   ¢     ¡   ¢     ¡  

Memory – p. 12/

provided by an active LOW chip enable (CE1), an active HIGHchip enable (CE2), and active LOW output enable (OE) and three-state drivers. Both devices have an automatic power-down feature (CE1), reducing the power consumption by

Standard SRAM: 6264
LogicBlock Diagram

The input/output pins remain in a hi the chip is selected, outputs are (WE) is HIGH. A die coat is used to

Pin C

I/O0 INPUT BUFFER I/O1 A1 A2 A3 A4 A5 A6 A7 A8 I/O2 I/O3 256 x...