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Conference vaxaxp::alphanotes

Title:	Alpha Support Conference
Notice:	This is a new Alphanotes, please read note 2.2
Moderator:	VAXAXP::BERNARDO

Created:	Thu Jan 02 1997
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	128
Total number of notes:	617

73.0. "MADD instruction on ALPHA architecture" by ZPOVC::SONALMEHTA () Mon Mar 31 1997 21:56

    I would like to know if MADD ( multiply-add instruction) is 
    supported on alpha architecture as it is supported on MIPS.
    From what I figured out it accelerates geometry processing
    in 3D graphic applications. Or do we have an equivalent 
    for this instruction ?
    The microprocessor I am refering to is 21164
    I would like to get the information as soon as possible.
    Thanks
    Sonal

T.R	Title	User	Personal Name	Date	Lines
73.1	Not included (for good reasons)	KAMPUS::NEIDECKER	EUROMEDIA: Distributed Multimedia Archives	`Tue Apr 01 1997 03:08`	3
	The Alpha architecture does not contain a multiply-add instruction. The 21164 can issue a multiply and an add in the same cycle though, giving a lot of the same effect.
73.2	move the discussion to clock rate and memory	WIBBIN::NOYCE	Pulling weeds, pickin' stones	`Tue Apr 01 1997 12:37`	3
	... and current 21164's run at 2x or 3x the clock rate of current MIPS 10000 processors, so you can actually complete a lot more multiply and add operations in the same time.
73.3	See RICKS::DEChips	XDELTA::HOFFMAN	Steve, OpenVMS Engineering	`Tue Apr 01 1997 14:23`	10
	This MADD issue sounds like FUD. See the EV56 variant of the 21164 (sometimes incorrectly, but uniquely and usefully, called the 21164A), for graphics support instructions. This would be better discussed in RICKS::DEChips -- there have been a number of discussions around the various tradeoffs, and around the new instructions added in EV56.
73.4	Graphics instructions coming, but not in systems yet	WIBBIN::NOYCE	Pulling weeds, pickin' stones	`Tue Apr 01 1997 14:26`	7
	Steve, you're thinking of the 21164PC, aka the PCA56. That's the one that added "Motion Video Instructions". This chip is sampling now, with volumes promised for summer (Northern Hemisphere). EV56 (the fast 21164 called 21164A except by DS marketing) added byte and word loads and stores, but not MVI.