[Simh] PDP7/DECsys bug

[Bob Supnik]

Does anything work? For example, does integer format output appear to 
be correct?  Other kinds of format specifiers, like H?

The problem could be in the simulator, or in the transcribed copy of 
the compiler or run-time library (the DECtape was nearly 40 years 
old).  There might be a clue based on what works and what doesn't.  If not...

The PDP-7 simulator has a history function that can record the most 
recent 65K instructions (and with a source change, even more than 
that).  You can use this to trace the doings of the simulator during 
the Fortran print statement.  Without source for the Fortran library, 
it will be difficult to understand what's going on, though.

/Bob Supnik



>----------------------------------------------------------------------
>
>Message: 1
>Date: Sun, 3 Jun 2007 08:44:25 +0300
>From: "Daniel Baum" <daniel at type34.info>
>Subject: Re: [Simh] pdp7/decsys bug?
>To: "SIMH List" <simh at trailing-edge.com>
>Message-ID: <006901c7a5a2$3ecf3380$0501c80a at IBM39EA7112605>
>Content-Type: text/plain; format=flowed; charset="ISO-8859-1";
>         reply-type=original
>
>
>Hi all,
>
>This is both an answer to the previous posts on this thread, and a report of
>some more progress in getting things to work on simh.
>
>I tried what Dave suggested. Decsys does not appear to be trying to use an
>unimplemented instruction. Therefore I still have not managed to solve the
>Decsys Fortran problem.
>
>To remind everyone what I'm talking about: Decsys Fortran does not seem to
>work properly with floating point values. It was suggested that it might be
>trying to call a floating point processor, but this does not seem to be the
>case.