Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: In defense of the VAX
Message-ID: <1989Feb26.023058.13906@utzoo.uucp>
Organization: U of Toronto Zoology
References: <11037@tekecs.TEK.COM> <76700073@p.cs.uiuc.edu> <324@taniwha.UUCP> <668@m3.mfci.UUCP> <501@megatek.UUCP>
Date: Sun, 26 Feb 89 02:30:58 GMT

In article <501@megatek.UUCP> mark@corona.UUCP (Rocket J. Squirrel) writes:
>One very BASIC goal of the project was to make sure that most of the 
>customer's PDP-11 code would run on whatever they built, since they hoped 
>to replace those PDP-11s with whatever they built.

This is a curious statement, given that the pdp11 emulation on the 780
omits floating point -- something that was very important to a lot of
customer software, especially for those high-end customers who would
be interested in an expensive new machine.  It omits some other things
as well, but those were less significant to the bulk of DEC customers.

>When the VAX-11/780
>first shipped, most of the software was taken directly from RSX-11 and
>ran under emulation.

Aha, now we get down to the nitty-gritty.  The explanation that best fits
the hardware is that pdp11 emulation mode was for running *DEC system
software* from the 11, with customer code very much a secondary issue.
-- 
The Earth is our mother;       |     Henry Spencer at U of Toronto Zoology
our nine months are up.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu