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Per Westermark
06/23/10 11:27
Read: 927 times
Sweden


 
#176870 - x bits are just one parameter among many
Responding to: ???'s previous message
Jez doesn't have any problems with larger/smallar packaging. They have a problem with smaller geometries. But if you run a 8051 core in a 0.13u geometry, you'll end up with similar result as an ARM core in 0.13u.

Limited capacity - the ARM chips don't require the user to try to move variables between different memory regions to maximize the speed or minimize the code size. That is a significant difference between the architectures. It's up to people to pay attention to details, whatever processor you have. Anyone thinking that with processor X everything will take care of itself is a fool and is best ignored.

Corroding pins? You shoudn't have any corroding pins. If you play in salty environments, you should look at conformant coating where everything is isolated. Using pin distance as a timer to decide the number of months/years the unit may survive before a failure is not a good metric.

Justin said:
Quite frankly, 32-bitters can do the same job an 8-bitter can do, maybe a little more poorly in some applications

Once more - that's a sentence that should read "A specific 32-bitter can get more or less spanked by a specific 8-bitter for a specific task." It is not the width of the ALU that decides when an 8-bit processor will win/lose over a 32-bit processor. It's how fell the instructions fits the task and/or the total crunching power and/or the worst-case response time and/or the amount of memory and/or the mapping from problem to peripherials, ... Being 32-bit just makes a processor "different" from an 8-bit processor. But as mentioned earlier, you can design a 32-bit processor with mnemonic-level support for every 8051 instruction, and able to run any 8051 instruction with the same number of clock cycles. If that is all you do, you'll waste the extra bits of the ALU. So you'll use wider instructions allowing the extra bits to describe new op-codes using 16- or 32-bit arguments. And you make sure that these extra instructions are valuable enough that they "pay for" the larger code flash needed to have all instructions consume n*16 or n*32 bits instead of n*8 bits. But since cost of a chip isn't proportional to the number of transistors, a processor with two or four times the number of code bytes can be sold at a lower price, if enough customers exists to make it meaningful to produce it in enough volumes using a good enough process.

Justin said:
If thats not true, then the 8-bitter will never vanish from the market.

There are no real driving forces to removing 8-bit processors from the market. It's only a subset of problems where 8 bits are a real disadvantage. Even if 32-bit processors can compete at lower and lower costs, the market suitable for 8-bit processors will still continue to grow since the total market for microprocessorcontrolled equipment will continue to grow. Who cares if there is an 8-bit or 32-bit processor in the keyboard? Of course - there is a better availability of 32-bit processors with USB interface so the 32-bit processors will take market shares. But as long as the power consumption continues to grow, there will always be new niches where microprocessors can be introduced. With a microprocessor in a lamp, you can get a smart lamp. Right now, we have RGB lamps that can randomly or by remote control change their color and intensity. We'll probably get more processor-controlled lamps.

It doesn't matter how much ARM grows. PC machines and simulation tools will also continue to grow. The day ARM leaves segments uncovered because they are so large that they can force their users into narrow tracks, "small" operators will be able to produce processors targeting these niches. Quite a lot of students have been tasked with designing their own processors (often not all the way to silicon but some students are lucky enough to study at the right university) so there will always be possibilities for unexpected competitors to jump in and grab market shares. Embedded applications often have short life spans, so compatibility with old code can often be ignored. This is a big difference from Windows and the ability/need to be able to run old PC applications.

The reason this thread started to debate ARM chips wasn't because the great love of ARM chips, but because this thread got a number of generalisations claiming that 8-bit processors in general and 8051 chips especially had magic advantages. One example was the ability to handle individual bits - but there are ARM chips that uses peripherial hardware to make the ARM core behave as if it had bit instructions. One example was the ability to read 8 bits at a time without need to isolate away the other 24 bits from a 32-bit port -but there are ARM (and other) chips that can do 8-bit reads/writes even if the core is 32-bit wide.

The thing here is that 8-bit or 80-bit is similar to one UART or two. It isn't in itself a critical selector unless the specific project has a specific need. Without the need for a second UART, it will only be a nice-to-have. If you don't need to be able to atomically add two 80-bit numbers, an 80-bit ALU will just be something nice-to-have. Anything existing with 80-bit ALU? Well the old x86 floating point unit did support 80-bit integers, but the reason people doesn't know about them is that not too many found them important to have and use. But how do we make sure that people starts a project with the right processor instead of trying to implement a second UART in software?

List of 104 messages in thread
TopicAuthorDate
So What Is An 8051/2 Good For?      Andy Neil      06/17/10 16:35      
   thoughts      Erik Malund      06/18/10 04:36      
      The Future of the 805x      Joseph Hebert      06/18/10 08:40      
         PARC      Rob Klein      06/18/10 09:01      
            Bigger Hammers      Joseph Hebert      06/18/10 09:37      
               re: Bigger Hammers      Rob Klein      06/18/10 10:59      
               The opposite problem seems more common here!      Andy Neil      06/18/10 15:50      
         Would Toyota have had the problem if ...      Erik Malund      06/18/10 09:31      
            Toyota: Case in point      Joseph Hebert      06/18/10 09:46      
            RE: Toyota      Andy Neil      06/18/10 10:17      
               It was a mechanical fix ...      Richard Erlacher      06/18/10 22:37      
            Parallel Processing      Justin Fontes      06/18/10 10:35      
               Sometimes the practical reality is of little consequence      Richard Erlacher      06/18/10 22:45      
                  Totally Agree, but I was looking for a magic bullet      Justin Fontes      06/18/10 23:09      
                  RE: "outperform"      Andy Neil      06/19/10 01:10      
                     There are some operations ...      Richard Erlacher      06/19/10 06:19      
                        rephrased      Erik Malund      06/19/10 06:44      
                        Now, you are extrapolating      Per Westermark      06/19/10 06:44      
                           good points, but      Erik Malund      06/19/10 07:12      
                              How many 8051 chips uses 0.13u?      Per Westermark      06/19/10 08:57      
                                 not yet      Erik Malund      06/19/10 13:05      
                           not exactly ...      Richard Erlacher      06/20/10 09:39      
                              Do not get focused on one operation...      Michael Karas      06/20/10 10:20      
                              any 8-bit instruction can exist in a 32-bit processor      Per Westermark      06/20/10 12:14      
                                 Yes, but does it?      Richard Erlacher      06/22/10 07:54      
                                    So have you looked at any other processors?      Per Westermark      06/22/10 09:37      
                                       not a point of disagreement, but you missed it anyway      Richard Erlacher      06/22/10 22:50      
                                          A good point      Justin Fontes      06/22/10 23:10      
                                             beg to differ      Michael Karas      06/22/10 23:23      
                                             Disagree entirely!      Andy Neil      06/23/10 00:45      
                                          Yes, auto-increment/decrement is standard and not "feature"      Per Westermark      06/23/10 00:29      
                                             What I wanted to point out ...      Richard Erlacher      06/23/10 06:07      
                                                Same same all the time. no "one size fits".      Per Westermark      06/23/10 07:46      
                                                   and the most important point is (drumroll) ....      Erik Malund      06/23/10 09:49      
                                                Comparing Apples to Oranges      Andy Neil      06/23/10 08:03      
                                          Prices are comparable      Andy Neil      06/23/10 01:00      
               Parallel processing        Oliver Sedlacek      06/22/10 02:40      
                  Sweeping generalisation!      Andy Neil      06/22/10 03:22      
                     Not a magic silver bullit      Per Westermark      06/22/10 04:20      
                        Fond memories      Oliver Sedlacek      06/22/10 07:58      
                        A magic bullet      Justin Fontes      06/22/10 10:17      
                           Most concepts already exists in the wild      Per Westermark      06/22/10 11:31      
                           Another generalisation        Andy Neil      06/22/10 14:43      
                           Speed vs latency      Oliver Sedlacek      06/22/10 14:47      
                              Why 8051?      Andy Neil      06/22/10 15:08      
                                 Isn't it obvious?      Justin Fontes      06/22/10 23:17      
                                    ARM simpler than 8051      Oliver Sedlacek      06/23/10 00:21      
                                       Generalisation      Andy Neil      06/23/10 01:34      
                                          ARM 'MCUs' have their limitations too!      Valentin Angelovski      06/24/10 07:52      
                                             You normally engineer with a backup plan      Per Westermark      06/24/10 08:20      
                                    No, it's not!      Andy Neil      06/23/10 01:27      
                                       Im just trying to provide an argument      Justin Fontes      06/23/10 10:33      
                                          x bits are just one parameter among many      Per Westermark      06/23/10 11:27      
                                             Avoiding the issue      Justin Fontes      06/23/10 21:09      
                                                Avoiding what issue?      Per Westermark      06/24/10 03:10      
                                          They say it because it's true!      Andy Neil      06/24/10 00:59      
                                          RE: ARM is not the only 32-bitter      Andy Neil      06/24/10 01:15      
                                    Please don'g generalize      Per Westermark      06/23/10 01:28      
                                 Heterogenous multiprocessing widespread      Oliver Sedlacek      06/23/10 00:17      
                  Re: Multicore 8051      Valentin Angelovski      06/24/10 06:48      
                     ALU chaining      Oliver Sedlacek      06/24/10 06:57      
   Well... maybe      Jez Smith      06/18/10 14:47      
      A Linear Accelerator?      Joseph Hebert      06/18/10 15:28      
         Its one of these      Jez Smith      06/18/10 15:51      
      please, repeat      Stefan KAnev      06/19/10 04:56      
         All I was saying was      Jez Smith      06/19/10 10:39      
   So what the '51 are good for...      Jan Waclawek      06/21/10 13:54      
      Not terribly helpful      Andy Neil      06/21/10 14:46      
         Always up to the developers      Per Westermark      06/21/10 15:24      
            RE: The manufacturers tells us...      Andy Neil      06/21/10 15:30      
               Sales - "may be used for" presented as "recommended"      Per Westermark      06/21/10 16:41      
               pretty hot, low-power and small      Maarten Brock      06/22/10 15:17      
                  Automotive...      Andy Neil      06/22/10 15:26      
         but answers your original question (at least the one...      Jan Waclawek      06/22/10 10:19      
         MCS51 still rocking !!!      Kiran V. Sutar      06/23/10 05:14      
            Scale      Andy Neil      06/23/10 06:09      
            Missing the point      Andy Neil      06/23/10 06:21      
               Impossible to generalize into fields      Per Westermark      06/23/10 08:09      
                  An appropriate generalisation...      Andy Neil      06/23/10 10:20      
               You are right..Andy Neil      Kiran V. Sutar      06/24/10 05:27      
                  Cheers!      Andy Neil      06/24/10 05:43      
                     No..only AT89C52 can be used      Kiran V. Sutar      06/24/10 05:56      
                        why do you insist on Atmel?      Erik Malund      06/24/10 06:05      
                        what a strange post      Erik Malund      06/24/10 06:09      
                        Tools?      Andy Neil      06/24/10 07:12      
                           Multiple manufactuers with (almost) identical chips      Per Westermark      06/24/10 07:48      
                              Getting better      Andy Neil      06/24/10 08:52      
                                 Unified interrupt controller is really great      Per Westermark      06/24/10 09:28      
                           Yes, even with free tools for PIC/AVR      Kiran V. Sutar      06/24/10 08:38      
                              I mean no offense, but ...      Richard Erlacher      06/26/10 09:59      
                              Similar difficulties coming to 8051/2?      Andy Neil      06/26/10 10:28      
                                 Same same      Per Westermark      06/26/10 11:18      
                  Is it your purchase price or why so sure AVR or PIC are off?      Per Westermark      06/24/10 05:55      
                     Answer to Per and Erik...      Kiran V. Sutar      06/24/10 06:38      
                  Living in the past      John D. Maniraj      06/24/10 09:44      
                     Thanks John D. Maniraj      Kiran V. Sutar      06/25/10 03:54      
                     locking      Erik Malund      06/25/10 07:20      
                        RE: Locking      Andy Neil      06/25/10 07:32      
                        Agreed, but      John D. Maniraj      06/25/10 11:00      
                           fairly easy      Erik Malund      06/25/10 11:53      
      Don't forget consumer devices      David Good      06/24/10 13:45      
         A perfect application      David Good      06/25/10 10:49      
   8051 vs ARM      Valentin Angelovski      06/24/10 08:34      
   just thought of one case      Erik Malund      06/24/10 12:32      

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