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???
10/17/08 21:21
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#159172 - I think a part number would be the solution
Responding to: ???'s previous message
Per Westermark said:
UVEPROM seems to be a good term when striving for clarity.

By the way: When was the last time a PC used RAM memory? The DRAM, Synchronous DRAM, Pipleline-Burst DRAM, ... are most definitely not random-access ;)

Somewhere along the line, we probably have to accept better than 10:1 as "near-enough" to be called RAM.


Then one could fairly assume (though it's not always the case!) that the datasheet had been examined.

Now, just what is it about DRAM, SDRAM, etc, that you don't see as random-access? It's true that synchronous DRAM is most generally used in bursts, mainly because the CPU has internal cache that needs loaded, but they can be randomly accessed. It's just faster to do it in bursts, so, when paired with a sizeable cache, it's likely to yield better performance to move data to/from it in bursts.

Back when we used plated-wire memory, cores, etc, those memories were random access enough, but core, for example required a special command in order to ensure the data wasn't damaged when read.

In some architectures, in order to speed up access to the relatively slow (1.2-1.5 microsecond) core memory, there were specific (read-only) memory commands, that were required when reading data that had to be refreshed in order to preserve it. A scratchpad often didn't require that. "Register" (they didn't have 'em, back then, values were stored in scratchpad. Rather than call and return using a stack, they used JST (jump and store) instructions, where the action was to load the address bus with the target address, store the PC at the target location and begin executing instructions after that location. When the subroutine ended it would jump to the return address stored at its beginning. That address certainly didn't have to be preserved.

RE




List of 41 messages in thread
TopicAuthorDate
MOVX doesn't work for writing.            01/01/70 00:00      
   It's a read-only memory            01/01/70 00:00      
      EEPROM            01/01/70 00:00      
         RAM-EPROM            01/01/70 00:00      
            That wouldn't be an EEPROM.            01/01/70 00:00      
            Look at Ferro-electric memory            01/01/70 00:00      
         Not wrong.            01/01/70 00:00      
            An EEPROM is an EPROM            01/01/70 00:00      
               Technically, but not in common usage of the term.            01/01/70 00:00      
                  Common use != Definition            01/01/70 00:00      
               Not quite ...            01/01/70 00:00      
                  No, it's not            01/01/70 00:00      
                  A datasheet that actually calls it a "UVEPROM"            01/01/70 00:00      
                     OK ... I stand corrected ...            01/01/70 00:00      
                        A link with EPROM <= EEPROM            01/01/70 00:00      
                        Not that generic!            01/01/70 00:00      
                           Magnetic core memory            01/01/70 00:00      
                           it is SERIAL EEPROM            01/01/70 00:00      
                              UVEPROM?            01/01/70 00:00      
                                 I think a part number would be the solution            01/01/70 00:00      
                                    Symmetric speed too.            01/01/70 00:00      
                           ta paidia paizei !!!            01/01/70 00:00      
            EEPROM implies EPROM            01/01/70 00:00      
               Today, it's the other way round.            01/01/70 00:00      
                  assumption < implication            01/01/70 00:00      
                  You missed the point!            01/01/70 00:00      
                     As one of my old tutors used to say...            01/01/70 00:00      
         Let's not confuse things further            01/01/70 00:00      
            You have also missed the point            01/01/70 00:00      
      Or...            01/01/70 00:00      
   Some Kind Like....            01/01/70 00:00      
      Non-Volatile Memory            01/01/70 00:00      
         or maybe the AT28C64B will work            01/01/70 00:00      
      You mean you want an NVRAM?            01/01/70 00:00      
   write eeprom            01/01/70 00:00      
      that may not be the problem            01/01/70 00:00      
         EPROM has special write-procedures            01/01/70 00:00      
   Check the write waveform timings!!!!!            01/01/70 00:00      
      How?            01/01/70 00:00      
         Source code to simulate MOVX...            01/01/70 00:00      
         Start with the datasheet ...            01/01/70 00:00      

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