Designing an FPGA Calculator from Scratch

(baltazarstudios.com)

54 points | by zdw a day ago ago

5 comments

  • defrost 6 hours ago

    Ten minutes in it looks like a great project walkthrough from design to physical device build.

    Good start for anyone interested in the guts of going from logic gates to math() primitives ( add, mult, tan, sin, etc ).

    Two snippets from the lede, one from a chapter heading:

      This is a scientific BCD calculator that uses binary-coded decimals, the same internal number format HP used in its scientific calculators going back to the 1970s. It represents every decimal digit as a 4-bit nibble, which means perfect decimal accuracy, no floating-point conversion errors, and an architecture that is genuinely shaped by the problem it solves. 
    
      Across ten chapters, you will follow full arc: the architectural decisions and tradeoffs, the numerical algorithms (addition, multiplication, CORDIC for trig, logarithms), the custom CPU design and its 12-bit instruction set, a hand-written two-pass assembler in Python, the microcode that runs on that CPU, a scripting layer for high-level key functions, and finally the physical board with its battery, display, and keyboard. 
    
    Chapter 6 (of 10):

      No general-purpose CPU has nibble-addressable memory and addressing modes designed to walk a 16-digit BCD mantissa — so this post designs one.
    
    I like it.
  • foota 4 hours ago

    I would love to have some real application that needs an FPGA :) Someday perhaps.

    • avmich 2 hours ago

      You would perhaps need to change the viewpoint for that. Theoretically, there is nothing which can't be achieved - functionally - without FPGA. However, that doesn't mean some problems can' be solved more conveniently using FPGA, and the solutions turn out better in some regards.

      • atultw 2 hours ago

        Could you share some of those applications which are better solved with an FPGA? As a student I have some ideas but am interested to hear more.

        • Imustaskforhelp 2 hours ago

          OTOH, I recently learnt that Jane street deploys their own FPGA servers for high frequency trade.