[Simh] pdp7/decsys bug?

[Carl Lowenstein]

On 5/15/07, Daniel Baum <daniel at type34.info> wrote:
> > Daniel wrote:
> >> I have had several successes (I will list them if anyone's interested),
> >> but
> >> I believe it is possible that there is a bug in the pdp7 simulator.
> >
> > Sorry I can't help you track down the bug, but I think it'd be great if
> > you posted your successes!
>
> Hi,
>
> Well, since you asked . . .  Here is what I have made work, with some
> impressions.
>
> I originally installed simh to get a look at the early unixes, and the early
> C compilers so:
>
>
> TSS/8 (PDP-8)  - a tiny multi-user system. Quite likeable. I managed to
> write programs in Basic and Algol, but had no success whatsoever with
> Fortran. Nothing compiles, including demo programs, leading me to assume
> that there is a file missing or something. I also managed to assemble a demo
> program with the assembler, but I think assembler is rather beyond the call
> of duty.

Four-decade-old memory of PDP-8 Fortran is telling me that there was
at least one variety that used the hardware Floating-point Unit.  This
was a rather rare beast that did 36-bit FP in three 12-bit host memory
words.  There may have been a software simulator for the FPU.

    carl
-- 
    carl lowenstein         marine physical lab     u.c. san diego
                                                 clowenstein at ucsd.edu