Date: Thu, 04 Feb 1999 20:48:26 -0800 From: Jason Thorpe <thorpej@nas.nasa.gov> To: Peter Wemm <peter@netplex.com.au> Cc: Stuart Krivis <stuart@apk.net>, freebsd-alpha@FreeBSD.ORG Subject: Re: alpha PC Message-ID: <199902050448.UAA06189@lestat.nas.nasa.gov>
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On Fri, 05 Feb 1999 11:54:24 +0800 Peter Wemm <peter@netplex.com.au> 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 <thorpej@nas.nasa.gov> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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