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Static Memory. Static Memory. Static Memory Systems. Those semiconductor components in a microcomputer that store the program and data.
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Static Memory Lecture 14 - Static Memory
Static Memory Lecture 14 - Static Memory
Static Memory Systems • Those semiconductor components in a microcomputer that store the program and data. • Role in the system can be seen as passive – memory simply stores information and except for specialized architectures, performs no operation on the data stored there. • Today it is common to have yyG bytes in a system. Lecture 14 - Static Memory
RAM Characteristics • Forms the bulk of memory in a system. • Today the bulk memory is typically a flavor of DRAM • Is read/write memory. • For read/write memory have choice of • Static RAM • Dynamic RAM • Special Characteristic Memory • ROM (PROM, EPROM, EEPROM) • EEPROM partially used as RAM • Computational Memory Lecture 14 - Static Memory
Static RAM • Nonvolatile – as long as power is on value is retained with no other action. Lecture 14 - Static Memory
Gate Equivalent Lecture 14 - Static Memory
1st approach to 16K of RAM Lecture 14 - Static Memory
2nd approach to 16K of RAM Lecture 14 - Static Memory
Internals of 6264LP Static CMOS RAM Lecture 14 - Static Memory
A RAM Chip • 6264LP-10 • -10 means 100ns access time • Consider all parameters Lecture 14 - Static Memory
Bus Contention • Read after read to same chip • Must consider what happens in preceding cycle and what happens in next cycle • Must also consider read after write, write after read, and write after write timing • Timing for the same chip and for different chips Lecture 14 - Static Memory
Read cycle bus contention Lecture 14 - Static Memory
Write cycle bus contention Lecture 14 - Static Memory
PROM and EPROM • Programmable Read Only Memory • One time programmable • Electrically Programmable Read Only Memory • Programmed by provided a higher than normal programming voltage – 12V to 25V • UV erasable • Used to program and code startup code – the bios in a PC Lecture 14 - Static Memory
PROM and EPROMS • Come in many sizes • Byte wide is very common • Worldwide is also common Lecture 14 - Static Memory
EEPROM • Another form of non-volatile memory • Read cycle is like other PROMs • Write cycle timing is long – typically over 100 us. Lecture 14 - Static Memory
EEPROMs and flash EEPROMs • Flash EEPROMs are similar to electrical erasable PROMs Lecture 14 - Static Memory
Example of flash EEPROM use • Flash EEPROMs are similar to electrically erasable PROMs Lecture 14 - Static Memory
Wikipedia provides some info • Wikipedia provides some useful overview of the topic of the various non-volatile technologies. Lecture 14 - Static Memory