Diehl Combitron (Was: "Oddball"(LGP-30)

[dwight elvey]

>From: "Rick Bensene" <rickb at bensene.com>
---snip---
>
>Slightly off-topic, but still within the "Classic Computer" realm: I'm
>currently in the process of doing this for the Wang 720C calculator.  I
>have successfully dumped the microcode out of the machine, and have
>written a simulator in Perl that simulates the hardware environment of
>the calculator, and executes the microcode.  I've still got a few minor
>glitches in the simulation, but for the most part, everything works.
>The only problem I have at this point is that for some reason, the base
>10 logarithm function gives a result that is the base e logarithm rather
>than the base 10 log.  The base e logarithm function (clearly) works
>fine.  The microcode appears to be heavily shared for these two
>functions, so there's probably something wrong with some implementation
>of the machine's logic in the simulation that causes a branch to be
>missed, or mis-interpreted.
---snip---

Hi Rick
I was going to mention that calculating logs is generally done the same
way in calculators, regardless of the base. They usually calculate it in
base 2 and then multiply by a constant to change to a different
base.
as an example:
    log2(n)*ln(2)=ln(n)
    log2(n)*log(2)=log(n)
  or if calculates the natural log first
    ln(n)*log(e)=log(n)
or even
    log(n)*ln(10)=log(n)   if it does decimal log first.
I hope this helps some.
Dwight

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