> On Jan 30, 2017, at 12:35 AM, Leo Broukhis <[email protected]> wrote:
>
> In the very first BESM-6 FORTRAN compiler -- the one derived from the CDC
> 1604 FORTRAN compiler by manually retargeting the assembly language source --
> there is a peculiar bug: the line
> IF (X=Y) stmt
> which should be rejected as syntactically incorrect (and is rejected by
> another, independently written compiler), does compile, and the resulting
> code is like
> X=Y
> IF(0.NE.0) stmt
>
> I'd like to check if the bug was there in the CDC compiler, or was introduced
> in the process of retargeting. As there is no CDC 1604 emulator in SIMH, CDC
> 1700 is the closest thing available (I know that their architectures are
> different; it's still worth checking in case the CDC 1700 compiler uses the
> same parsing algorithm).
>
> Does anyone have the knowledge how to run FORTRAN on the CDC 1700 emulator?
>
> Thanks,
> Leo
>
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Leo,
The MSOS installation described in CDC1700-MSOS.txt includes the Fortran
compiler. Unfortunately, both the assembler and fortran compiler cause a
protection fault (jp01) when run. I believe this is due to the emulator being
based on the original instruction set definition which included a number of
“unused” bits in certain instructions. Later implementations of the
architecture (using the MP17 microprocessor to emulate the 1700 instructions)
added enhancements to the instruction set which redefined these bits - MSOS
assumes that it is running on one of these later implementations. I’m actively
working on allowing the emulator to run in multiple modes; the original
instruction set and the basic instruction set which will treat enhanced
instructions as a NOP. I just started this a few days ago and have no idea how
long it will take.
John.
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