Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!sdrc!cinnet!kilian From: kilian@cinnet.com (Kilian Jacob) Newsgroups: comp.sys.amiga.hardware Subject: Re: My A3000/25/50 seems a bit slow... Why? Message-ID: <1991May13.201603.1388@cinnet.com> Date: 13 May 91 20:16:03 GMT References: <21451@cbmvax.commodore.com> Organization: Cincinnati Network, Cinti. OH Lines: 27 From article <21451@cbmvax.commodore.com>, by daveh@cbmvax.commodore.com (Dave Haynie): > per longword. So that makes Fast RAM somewhere between 3x and 5x faster than > Chip RAM, even when Chip RAM isn't loaded down with lots of video fetch, > blitter, or copper activity. And Fast RAM, of course, never gets loaded down. > So, basically, you want Fast RAM in your A3000 for anything that doesn't > absolutely have to live in Chip RAM. > > This is really the same on practically every computer, they just don't make > their "Chip RAM" flexible enough to contain anything but a video display. You > wouldn't, for example, run programs out of the display buffer in a VGA card > on a PC Clone. This will always be the case on Amigas. Even with faster ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > systems way in the future, Chip RAM will always be optimized for the needs of > the video chips, while the Fast RAM will always be optimized for the needs of > the processor bus (CPU, FPU, DMA for SCSI, whatever else lives here). > But it *was* not always true for the Amiga. I think the way the CPU/DMA CHIP RAM access is timed on a 68000 based Amiga was *the* unique feature of the Amiga hardware. Well, it would have been rather expensive to reimplement this "perfect" bus timing in a similar way on a 68030 based system. -- /