From owner-freebsd-alpha Thu Feb 4 20:48:39 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id UAA24818 for freebsd-alpha-outgoing; Thu, 4 Feb 1999 20:48:39 -0800 (PST) (envelope-from owner-freebsd-alpha@FreeBSD.ORG) Received: from lestat.nas.nasa.gov (lestat.nas.nasa.gov [129.99.50.29]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id UAA24813 for ; Thu, 4 Feb 1999 20:48:38 -0800 (PST) (envelope-from thorpej@lestat.nas.nasa.gov) Received: from lestat (localhost [127.0.0.1]) by lestat.nas.nasa.gov (8.8.8/8.6.12) with ESMTP id UAA06189; Thu, 4 Feb 1999 20:48:27 -0800 (PST) Message-Id: <199902050448.UAA06189@lestat.nas.nasa.gov> To: Peter Wemm Cc: Stuart Krivis , freebsd-alpha@FreeBSD.ORG Subject: Re: alpha PC Reply-To: Jason Thorpe From: Jason Thorpe Date: Thu, 04 Feb 1999 20:48:26 -0800 Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, 05 Feb 1999 11:54:24 +0800 Peter Wemm wrote: > etc. In the console code is embedded a copy of "palcode". Palcode is > both a blessing and a curse. It's the low level pseudo-microcode that > provides a personality for the execution environment. It is meant to Ah ah ah! It's not microcode! Remember, this is a RISC system! Thar be no microcode here! What really sets PALcode apart is that it is written in the standard Alpha instruction set. It *does* use some facilities only avalable to PALcode, e.g. the hw_* instructions (which are different from Alpha processor model to model) and the IPRs (internal processor registers). But, it's really just a program, much like a kernel, which runs at a higher privilege level (PAL mode). > The NT palcode basically tries to make the Alpha look as much like a PC as > it can get away with. Well, sort of a cross between PC and MIPS :-) NT, even on the i386, requres a "veneer" program which presents a sort of ARC-like console :-) NT is a lot less x86-centric than a lot of people think. > restore the 64 bit environment or something like that. It can then run > Unix-like OS's that were intended to run under a SRM environment and real > OSF palcode with a lot less pain than trying to run in a > sanitized-to-avoid-confusing-NT environment. err, OSF/1 PALcode environment. There's at least one commercial Alpha system which ships with a non-SRM console, but has OSF/1 PALcode. -- Jason R. Thorpe To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message