Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!apple!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga Subject: Re: A2630 questions Message-ID: <9442@cbmvax.commodore.com> Date: 23 Jan 90 19:17:23 GMT References: <1251@crash.cts.com> Organization: Commodore, West Chester, PA Lines: 103 in article <1251@crash.cts.com>, pierre@pro-graphics.cts.com (Peter Altamore) says: > It's my understanding that the A2630 comes with 2 megs of RAM soldered > onboard and has room to solder 2 additional megs, to bring it up to 4 > megs of 32-bit RAM. That's true. However, there is a daughterboard connector on the A2630 which will logically support the addressing of 64 megabytes of 32 bit memory. Or a cache. Commodore hasn't announced any A2630 daughterboards yet, and you'd have to be pretty clever to stuff 64 megabytes on a board that size using current DRAM technology, but the upgrade path is there. > It is also my understanding that the A2630 is an asynchronous design that'll > allow for the addition of an 030 that's faster than the 25MHz one currently > implemented. I have 2 problems with this: [2] How can I upgrade to a faster > processor if adding faster RAM means soldering and de-soldering sensitive and > expensive RAM chips? An "asynchronous" design, as in reference to an Amiga CPU slot board, is simply a claim that the CPU speed is not not coupled to the speed of the motherboard or video clocks. That's all it's saying. It does not imply that you can drop in a faster CPU and go faster. And there are many issues related to going faster that have nothing to do with RAM speed. You can't expect to drop in a faster CPU, memory, and crystal into a arbitrary asynchronous board any more than you can drop a faster 68000, memory, and crystal into the A2000 itself and go faster. On the other hand, it's possible to design a system where the memory and CPU speeds are basically decoupled. > The first problem is the most pressing, I DO anticipate having an 8 meg 030'ed > machine by summertime and it seems like the A2630 won't be the ticket. No one's forcing you to buy the A2630 or any other 68030 card. Obviously, if the A2630 were the ultimate answer every Amiga owner was looking for in the accelerator market, a few other companies would be in trouble. Some others may claim to be upgradable to a faster clock speed, but don't expect any current design to just up and run when you drop in that 50MHz CPU and crystal and some 50ns DRAM. There's just much more to systems design than plug and chug. No matter who you buy from, if expect to upgrade to a specific CPU speed, GET IT IN WRITING. From a reputable company, too. > I'm also having problems finding someone to reconcile some other RAM > considerations I have. Is it possible to have an AT Bridgeboard AND and 030 > card with 8 megs? I realize that the AT Bridge takes up considerable 68000 > address space. Will peripherals that are on the 68000 bus (in the slots) > affect the amount of RAM that the 030 can use? What will happen if I have 4 > megs of 16-bit RAM AND 8 megs of 32-bit RAM? All of this depends on where things are mapped. Autoconfig space is by definition an 8 megabyte chunk of memory from $00200000-$009fffff. All 16 bit cards sit there (except for very small I/O typs cards, which have another small space they can live in). All autoconfig cards live there too. If your 32 bit memory is autoconfiguring, it takes away some of the space used for 16 bit cards. A bridge card takes up 2 megs. If you have 8 megs of autoconfig memory on an 68030 card, you can't have the bridge card at the same time. It's up to the designers if that 32 bit memory can be mapped elsewhere and AddMemed. However, having ONLY AddMemed 32 bit memory will slow down your DMA performance with hard disks. These are what we call trade-offs. > What this all boils down to is that the GVP 030 card seems like a much > more logical and sound design (please disspell this if it isn't true! ). Translation: The GVP card seems to meet your needs better than the A2630. It very well may. Commodore had certain requirements for the A2630. First was that it have on-board 32 bit memory, since a 32 bit CPU is crippled without it. You could certainly build a bigger and possibly faster memory system, given the space of a whole card, than you can in the corner of an already-full Coprocessor card. Commodore also required a 2 megabyte option, which does limit a number of the "tricks" you can play with the 68030 to make things go a little faster. GVP obviously had different requirements and goals. Neither of these are wrong. > I've also 'heard' that the A2630 has wait states! Please tell me this > isn't true! All 25MHz 68030 systems using DRAM have wait states. To run without wait states you need a memory _cycle_ time of 80ns. To put this in prespective, an 80ns DRAM has a _cycle_ time of around 150ns, a 100ns DRAM have a cycle time of around 190ns. Anyone who claims they're running 0 wait states is using major trickery or lying to you; probably both. There are some standard techniques for getting a little more performance out of your memory; they all require larger memory banks (4 meg a chunk) or more logic, probably both. The A2630 goes as fast to 100ns memory as a 25MHz 68030 can without resorting to any real cleverness that would violate the design constraints (eg, the design fits on the A2630 card and can support both 2 and 4 meg configurations). > I want the price that the Commodore solution provides, but it seems like > the product design (A2630) has been *seriously* compromised for one > reason or another. Thank you for your time. I don't know what you heard, but you're confused. There are some tradeoffs in the A2630 design, just like any other design in existence. You may or may not agree with the direction it went in; I may not either -- Commodore made the choices. I just designed it for them. But there are no serious comprimises. > ProLine: pro-generic!pro-graphics!loginID | Pro-Graphics 24hrs -- Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Too much of everything is just enough