Path: utzoo!mnetor!uunet!steinmetz!sunset!oconnor
From: oconnor@sunset.steinmetz (Dennis M. O'Connor)
Newsgroups: comp.arch
Subject: Re: RPM-40 microprocessor @ 40 MHz; data from ISSCC
Message-ID: <9656@steinmetz.steinmetz.UUCP>
Date: 23 Feb 88 16:06:32 GMT
References: <1642@mips.mips.COM>
Sender: news@steinmetz.steinmetz.UUCP
Reply-To: sunset!oconnor@steinmetz.UUCP
Organization: GE Corporate R&D Center
Lines: 38
Keywords: General Electric, DARPA-MIPS-core-ISA

An article by bcase@apple.UUCP (Brian Case) says:
] In article <1642@mips.mips.COM> mark@mips.COM (Mark G. Johnson) writes:
] >
] >   
] >Several articles have recently appeared, alluding to a CMOS  uP
] >built by General Electric, e.g. <9629@steinmetz.steinmetz.UUCP>,
] ><9631@steinmetz.steinmetz.UUCP>, and <375@imagine.PAWL.RPI.EDU>.
] >
] >Branch instructions _seem_ to have only a 12-bit displacement field;
] >there doesn't appear to be a "Branch Register", "Branch And Link",
] >or "Conditional Branch" instruction.  Perhaps the "COND" instruction
] >is the conditional-skip instruction recently mentioned on the net**.
] 
] Allen Baum (who attended the conference) told me that the single branch
] instruction is only available in the conditional form.  Thus, for
] an unconditional branch, you must make sure that you know the state of
] the single boolean bit (compares test a condition and set the state of
] the boolean bit).

Allen Baum has misinterpretted. Branches are conditional-ized just
like any other instruction (except PREFIX). If and only if the branch
(and its PREFIXes, if any) are preceeded by one or more COND
instructions (and there PREFIXes, if any) is the branch conditional.
 
] >11. A simple virtual memory scheme called "most significant bit replacement"
] >    is used.  A process-id is appended to the MSB's of an address before
] >    sending it out of the CPU.  A special case occurs when those bits
] >are all-0's or all-1's.... ** **
] 
] Isn't this the original Stanford MIPS scheme?

It's an enhancement of the original Stanford scheme.


--
	Dennis O'Connor 	oconnor@sunset.steinmetz.UUCP ??
				ARPA: OCONNORDM@ge-crd.arpa
    "Nuclear War is NOT the worst thing people can do to this planet."