Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!orion.oac.uci.edu!uci-ics!ucla-cs!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga.hardware Subject: Re: A3000 CPU slot Message-ID: <11321@cbmvax.commodore.com> Date: 4 May 90 13:22:07 GMT References: <11207@cbmvax.commodore.com> <11007@shlump.nac.dec.com> Reply-To: daveh@cbmvax (Dave Haynie) Distribution: comp Organization: Commodore, West Chester, PA Lines: 36 In article <11007@shlump.nac.dec.com> guineau@wjg.enet.dec.com writes: >>>1. Does it operate in the same way as the one in the 2000? >>> That is take over from the motherboard CPU. >>Yes. There are actually several takeover and clocking options for >>a Coprocessor slot card. >Take Over! [..] an 'extra' 68030 hanging around the mother board >seems like an awfull waste... Just like in the 2000, a Coprocessor slot device can take over all system operations from the motherboard processor, becoming a full fledged primary bus master and the one and only CPU active in a uniprocessor configuration. However, you will notice that I call this slot the "Coprocessor" slot. Just like on the 2000, a Coprocessor slot device can only take over the motherboard bus for short bursts, keeping the motherboard '030 active the other times. On top of this, there are actually two different mechanisms to effect either of these transfer-of-control operations; one that's very much like a normal 68030 bus arbitration, and one that's a modified 68030 bus arbitration: a bit of additional complexity, but it's very fast. So, in other words, the Coprocessor slot card can take over completely or run in parallel with the motherboard CPU. In the latter case, that coprocessor slot CPU will need some private memory so that it's not eating up all the motherboard bus bandwidth. >W. John Guineau guineau@wjg.enet.dec.com >Digital Equipment Corporation >Marlboro MA. 01752 -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "I have been given the freedom to do as I see fit" -REM