Path: utzoo!yunexus!unicus!craig From: craig@unicus.UUCP (Craig D. Hubley) Newsgroups: comp.sys.amiga Subject: Re: Hey, Commodore Sales: Amiga 3000 Warning Message-ID: <2520@unicus.UUCP> Date: 12 Apr 88 21:48:51 GMT Article-I.D.: unicus.2520 Posted: Tue Apr 12 17:48:51 1988 References: <7735@oberon.USC.EDU> <247@sdrc.UUCP> <930@rmi.UUCP> <61@kenobi.UUCP> <2503@unicus.UUCP> <1359@hubcap.UUCP> Reply-To: craig@Unicus.COM (Craig D. Hubley) Organization: Unicus Software Inc., Toronto, Ont. Lines: 77 In article <1359@hubcap.UUCP> rchampe@hubcap.UUCP (Richard Champeaux) writes: >In article <2503@unicus.UUCP>, I write: >> If you produce a Zorro III standard (32-bit, access to video, etc.), >> then it *must* somehow be able to support a Zorro II card, *in* the cage. I stand by this statement. > Your right, if the 68030 is anything like the 68020, it is capable of >dynamic memory port sizing, and would have no problem addressing a 16-bit >card. However, if that card has DMA on it connected to some I/O device, >then it would need to be able to address the 32-bit memory that is most likely >to exist in an A3000. Getting a card that is connected only to D0-D15 of the >address bus to access the odd addressed words connected to D16-D31 would >require extra hardware on each of the 32-bit memory cards that would allow >word swapping. It might be possible to put such hardware on the system board, >but that would make it really complicated, and probably slow up the bus. But you could always *bypass* this stuff when it wasn't being used, and not slow up the bus. I never said there wouldn't be a performance hit for this, but the bus and processors will be faster anyway. And you could always go my `third option' of supporting a separate cage (perhaps a 2000-and-1). >Another idea that was suggested by someone a few messages ago, was to include >some 16-bit memory for the 16-bit cards to use, but to do that, you would have >to require software wishing to use such devices, to place anything it wants >DMA'ed in the 16-bit memory. Now your hardware is compatable, but your >software doesn't work anymore. Remember that you probably already have a 16-bit memory card, in fact you definitely have one if you have expanded your machine at all. Why not just use *that* memory ? Anyway, an answer to the software question is to have FAST memory be 16-bit, by definition, and FASTER memory, or something, be 32-bit. You would want to recompile your software under a 32-bit environment anyway, so requiring such a change is no big deal, and everything else would work in the meantime. Since it's all written in C, it probably makes tons of assumptions of sizing anyway, and would need to be adjusted to work. The Amiga nicely supports 68000-020, but I'm not sure if it extends as far as a 32-bit bus, without needing recompilation. Anyone knowledgeable want to comment. You could always have a `give 16-bit memory only' mode for those incredibly sensitive applications, which could be adjusted to make the ] distinction later. I know this sounds Intel-ish, but look how many machines get sold with `this will work as is, no changes' 8088 emulation mode. The smart folks would bypass it with code that took advantage of the new goodies, and in the meantime the old stuff would all work, adn *be cheap*. > Anyways, if the A3000 is indeed aimed at the workstation market, and has >the accompanying price of $4000 plus, then the A2000 will still be a very >popular computer (probably more popular than the A3000). I hardly think that >CA will drop, or that people will stop buying the A2000, so you won't have >to worry about companies dropping their Zorro-II cards. Right. So now I must buy new Zorro III cards to replace all my old Zorro II cards that work just fine, taking a loss selling my old ones. This is still nasty. I'm not worried about dropping Zorro II, I'm worried about the wait as people decide whether or not to start up Zorro III design/production. Expect a year wait before the selection is as good as an A2000, and in the meantime the machine may die. I'd probably buy a SPARC machine instead, since I would have to replace my whole configuration anyway, might as well use what AT$T, $un, and Xerox use. After all,they write the software that I want to use. And eventually, companies *would* drop their Zorro II cards. More importantly, I'd be afraid to buy anything new for my Zorro II machine for fear that the replacement cost when I moved up to an A3000 (still running Unix) would be prohibitive. I'd save my money for the new one, and do without the capabilities in the meantime. Good for no one. My argument stands. >Rich Champeaux >Clemson University I still think this is a month's engineering effort for a design team, and maybe $50 of hardware and a few badckwards-compatible software tricks, to gain many potential customers and save everybody upgrading a year's wait. A smart company would do it, at least as an option. Craig Hubley, Unicus Corporation, Toronto, Ont. craig@Unicus.COM (Internet) {uunet!mnetor, utzoo!utcsri}!unicus!craig (dumb uucp) mnetor!unicus!craig@uunet.uu.net (dumb arpa)