Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!leah!albanycs!crdgw1!uunet!mcvax!kth!draken!tut!tucos!moj
From: moj@utu.fi (Matti Jokinen)
Newsgroups: comp.arch
Subject: Re: DECSYSTEM 20
Message-ID: <929@tucos.UUCP>
Date: 16 Jul 89 19:53:46 GMT
References: <3256@wpi.wpi.edu>
Reply-To: moj@polaris.utu.fi (Matti O. Jokinen)
Organization: University of Turku, Finland
Lines: 12

>One interesting thing about the DEC 20 (and I guess DEC 10 and
>pdp-6 as well) is that the registers are the first 8 or 16 locations in the
>main memory map.  Does anyone know if code can be run in the registers?  And
>if so, does it execute any faster than if it was in normal memory?

Yes, it could be done and it was considerably faster at least in the older
DEC-10 models.  I remember reading that a separate register set was not an
essential part of the architecture --- if it was removed, the first 16 words
of the main memory were used instead and the machine still functioned
correctly, only more slowly.
--
Matti Jokinen