From: alexfrunews@gmail.com   
      
   On Friday, November 25, 2022 at 5:44:46 PM UTC-8, muta...@gmail.com wrote:   
   > I vaguely recall someone saying that   
   > old thinking, from 70s or 60s I think,   
   > was that data registers and address   
   > registers would all be the same size.   
   >   
   > Or something like that.   
   >   
   > With the exception of the circumstance   
   > where segmentation is required, it's   
   > true, isn't it? Everything is or can be   
   > the same size, simplifying things.   
   ...   
      
   Things get simplified in the compiler when the CPU   
   registers are uniform.   
   But it's not necessarily segmentation.   
   Just separating code from data and supporting   
   different sizes of the two spaces asks for differently   
   sized pointers, one of the two of which is inevitably   
   going to differ from the data register size.   
   On top of that, the data registers may be sized   
   for specific tasks. For example, if I remember it correctly,   
   TI's TMS320C54xx has 2 40-bit accumulators, a bunch of   
   16-bit data address registers (which support some ALU   
   operations as well, not just memory addressing) and a   
   segmented program counter (16+16 bits). Oh, and the byte/char,   
   short and int are all 16-bit.   
   40-bit accumulators let one multiply-accumulate 256 or 512   
   pairs of 16-bit integers (to perform the basic DSP operation of   
   signal filtering/convolution).   
   You don't need to use all 40 bits all the time, you can just   
   use the 16-bit or 32-bit parts of each accumulator.   
   Just an example of a contemporary non-uniform arch.   
      
   Alex   
      
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