Mainframe floating point math implementation.

Charles Anthony at
Sun Mar 27 21:43:00 CDT 2016

On Sun, Mar 13, 2016 at 1:39 PM, Charles Anthony < at
> wrote:

> The Multics distribution includes ISOLTS, a surprisingly complete and
> pedantic processor test program.
> It is unhappy with our emulated floating point.
> I've abstracted the instruction out of the emulator and embedded it in a
> standalone test harness that runs the 47 tests.
> Any insights, suggestions for algorithms, reading material would be
> greatly appreciated.
After many helpful suggestions and analyses, the missing piece of the
rounding algorithim has been identified:

   Only round if the mantissa was shifted more then 71 bits.

Many thanks,

-- Charles

More information about the cctech mailing list