[Simh] OS development

[Johnny Billquist]

On 2015-06-12 11:53, Timothe Litt wrote:
> On 11-Jun-15 09:17, Johnny Billquist wrote:
>>
>> DAP is good until 2070 or so. If the DAP implementation on
>> Tops-10/TOPS-20 don't do things right at the moment, it's just a local
>> bug within those OSes then. RSX and VMS (maybe others) have had DAP
>> Y2K secure for many years.
>>
> DAP for Phase III/IV (V5.6.0) has 2-digit years.  I'm not sure how we
> let such a dumb mistake get thru the architecture process, but we did.
>
> T10/20 didn't implement PhaseV, which I haven't looked at.  T10/20
> development stopped long before Phase V was defined.
> Upgrading to Phase V DAP is likely more than "a local bug" fix; it's
> real work.

RSX don't have phase V either.
Yes, the year field in DAP is just two digits. But it's not 19xx. It's 
actually 1970 - 2069 or some such.

>> I thought the Tops-10/TOPS-20 stuff was handed over to XKL, but maybe
>> someone with better knowledge than me can clarify this.
>>
> No. XKL had/has a license and could sub-license for use on their
> hardware, but DEC retained ownership.  I was peripherally involved.

Ok.

>> The legal jungle around the PDP-11 software is a nightmare. The PDP-10
>> stuff is easy in comparison, I think.
>>
> Easy is alway relative to who has to do the work :-)

Definitely true. But good luck even finding someone who know what you 
are talking about if you start contacting HP about the PDP-11 stuff. 
Since it was sold off to Mentec, but DEC retained some control rights, 
it is really confused. And I doubt anyone is left who was around when it 
was worked out. And I wouldn't be surprised if even those people didn't 
entirely understand what they created.

	Johnny


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