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???
01/06/10 23:56
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#172210 - Proper methodology can't really bound the memory requirement
Responding to: ???'s previous message
Marty Mcleod said:
32K (or less!) RAM is more than enough in some larger applications. Even 8K or whatever is sufficient when applied properly and when you've clearly defined your design requirements and are using proper software programming methodology.

We ran a whole board successully with one Silicon Lab. 8051 w/ 4K XRAM.

There are no simple figures what is "enough" memory in a processor, even if the developer is skilled. It's just a question of what type of problems that are solved.

Ask Erik for example - when playing with displays, he wants frame-buffer memory for his pixel-mapped displays. The amount of RAM, and the bandwidth allowed for sending out the data, defines how large display that can be serviced with one processor, before it gets time to add in more processors.

On the other hand, the advent of FRAM memory has greatly changed the ability to use large nonvolatile memory to store large amounts of data even if that data needs to be regularly modified. With older technologies like EEPROM or flash, it isn't possible to use serial or parallell-connected nonvolatile memory as scratch memory since it is quite easy to run through 10k, 100k or 1 million write cycles. And advanced wear-leveling algorithms can help in some part, but does require an extra layer of complexity that both slows down an application and potentially adds hard-to-catch bugs.

But in the end, it will be simple to find suitable embedded projects where a processor with quite low computation capabilities may be used, but where the amount of storage space for quickly changing state information may be quite high.

When extending an existing project, it is normally easiest to keep going with the same processor architecture, and find something with more internal RAM, or find cheap external memory chips to add. When starting from scratch, it is normally better to not be locked into the existing knowledge of processor architectures but to instead shop around among the large number of architectures that exists, to find a cheap solution that seems to fit well to the problem and that may have better growth capabilities in case the product is a success and people starts to ask for upscaled deluxe editions of the product.

List of 26 messages in thread
TopicAuthorDate
Need more Internal RAM            01/01/70 00:00      
   Yes, but they handle it the same as external RAM            01/01/70 00:00      
   Look here            01/01/70 00:00      
      Ok            01/01/70 00:00      
   complicated and complicated            01/01/70 00:00      
   why?            01/01/70 00:00      
   It's Not Really So Complicated--And....            01/01/70 00:00      
      someone recently posted a link to a 805x with 64kB of RAM            01/01/70 00:00      
      Proper methodology can't really bound the memory requirement            01/01/70 00:00      
      That's My Point            01/01/70 00:00      
   RAM expansion need not be complicated!            01/01/70 00:00      
      MOVX problem            01/01/70 00:00      
         No            01/01/70 00:00      
            unless you have external glue logic            01/01/70 00:00      
               Yes            01/01/70 00:00      
         "bible" time!            01/01/70 00:00      
      There are much larger SPI memories            01/01/70 00:00      
   Look at Wiz chip            01/01/70 00:00      
      Link?            01/01/70 00:00      
         links            01/01/70 00:00      
            Overkill?            01/01/70 00:00      
               and expensive?            01/01/70 00:00      
                  When at electronics store            01/01/70 00:00      
                     Which one?            01/01/70 00:00      
                     How does that compare with ordering from outside?            01/01/70 00:00      
                        I've always had to do that!            01/01/70 00:00      

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