Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-03-02 Thread allison via cctalk
On 03/02/2018 06:44 AM, Maciej W. Rozycki via cctalk wrote: > On Wed, 28 Feb 2018, Paul Koning via cctalk wrote: > >> With the VAX, this got cleaned up to a significant extent, and ditto >> with Alpha. In both cases, an internal validator tool was created to >> verify that, at least from the

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-03-02 Thread Maciej W. Rozycki via cctalk
On Wed, 28 Feb 2018, Paul Koning via cctalk wrote: > With the VAX, this got cleaned up to a significant extent, and ditto > with Alpha. In both cases, an internal validator tool was created to > verify that, at least from the point of view of instruction execution, a > new machine worked the

RE: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-28 Thread Rich Alderson via cctalk
From: Doug Ingraham Sent: Wednesday, February 28, 2018 9:53 AM > This is a great story! And it probably indicates that when developing the > Toad-1 this particular diagnostic was never run from an original DEC generated > tape or the Toad-1 would have failed the diagnostic. Alternatively

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-28 Thread Chuck Guzis via cctalk
On 02/28/2018 10:55 AM, Paul Koning via cctalk wrote: > In general, manuals are only a rough approximation of reality. I > remember an old joke that "PDP-11/x is compatible with PDP-11/y if > and only if x == y". And sure enough, if you look at the models > appendix of the PDP-11 Architecture

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-28 Thread Paul Koning via cctalk
> On Feb 28, 2018, at 1:10 PM, David Bridgham via cctalk > wrote: > > >> Imagine our chagrin when days of trying to correct the >> problem led to the conclusion that the diagnostic was incorrect. > > I may have a situation like this in working on my FPGA PDP-10. The

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-28 Thread David Bridgham via cctalk
> Imagine our chagrin when days of trying to correct the > problem led to the conclusion that the diagnostic was incorrect. I may have a situation like this in working on my FPGA PDP-10.  The Processor Reference Manuals seem quite clear that the rotate instructions take E mod 256.  One of the

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-28 Thread Doug Ingraham via cctalk
On Tue, Feb 27, 2018 at 2:46 PM, Rich Alderson via cctalk < cctalk@classiccmp.org> wrote: > > Fast forward 20 years, to Living Computer Museum, where a KI-10 based > DEC-1070 > was undergoing restoration. Diagnostics were needed, so the resident > TOPS-20 > programmer laid hands on the MAINDEC

Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

2018-02-27 Thread Rich Alderson via cctalk
From: Paul Koning Sent: Monday, February 26, 2018 12:19 PM >> On Feb 26, 2018, at 12:06 PM, Doug Ingraham via cctalk >> > wrote: >> The purpose of an emulator is to accurately pretend to be the original >> hardware. It doesn't matter that the original OS runs on a