1. 9/20/6Lecture 14 - Static Memory1 Static Memory

2. 9/20/6Lecture 14 - Static Memory2 Static Memory

3. 9/20/6Lecture 14 - Static Memory3 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 to 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.

4. 9/20/6Lecture 14 - Static Memory4 Static RAM Characteristics  Forms the bulk of memory in a system.  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

5. 9/20/6Lecture 14 - Static Memory5 Static RAM  Nonvolatile – as long as power is on value is retained with no other action.

6. 9/20/6Lecture 14 - Static Memory6 Gate Equivalent

7. 9/20/6Lecture 14 - Static Memory7 1 st approach to 16K of RAM

8. 9/20/6Lecture 14 - Static Memory8 2 nd approach to 16K of RAM

9. 9/20/6Lecture 14 - Static Memory9 Internals of 6264LP Static CMOS RAM

10. 9/20/6Lecture 14 - Static Memory10 A RAM Chip  6264LP-10  -10 means 100ns access time  Consider all parameters

11. 9/20/6Lecture 14 - Static Memory11 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

12. 9/20/6Lecture 14 - Static Memory12 Read cycle bus contention

13. 9/20/6Lecture 14 - Static Memory13 Write cycle bus contention

14. 9/20/6Lecture 14 - Static Memory14 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

15. 9/20/6Lecture 14 - Static Memory15 PROM and EPROMS  Come in many sizes  Byte wide is very common  Wordwide is also common

16. 9/20/6Lecture 14 - Static Memory16 EEPROM  Another form of non-volatile memory  Read cycle is like other PROMs  Write cycle timing is long – typically over 100 us.

17. 9/20/6Lecture 14 - Static Memory17 EEPROMs and flash EEPROMs  Flash EEPROMs are similar to electrical erasable PROMs

18. 9/20/6Lecture 14 - Static Memory18 Example of flash EEPROM use  Flash EEPROMs are similar to electrically erasable PROMs