Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!diemen!tasman!steveh From: steveh@tasman.cc.utas.edu.au (Steven Howell) Newsgroups: comp.sys.mac.hardware Subject: Re: IIfx RAM access Message-ID: Date: 24 Mar 91 06:12:53 GMT References: <1991Mar14.024009.5193@mintaka.lcs.mit.edu> Sender: news@diemen.utas.edu.au Lines: 21 Well, the mac IIfx does use dual ported RAM, basically, it means it has two lines that data can be sent to the chip thru. There are a couple of diffrent types of this memory, and it does run faster via the ability to read and write more efficently, not via chemical speed levels ie 80ns 100ns etc. The main advantage of this type of memory, is the ability to read and write virtually simultaneously. An obvious example of how this could be used to increase speed would be in the video. Normally only one device could have access to the chip, meaning another would have to wait until the first was finished. But dual port memory can be serviced by two devices, and in a video situation this is ideal, as the video circuit can read the data to be displayed whilst at the same time, but and address behind, the processor can update the new data to be displayed next, all without the two devices needing multiplexed access lines. Basically saves time, and makes things simpler. Anyway, see how that helps you out. Steve h