tinyguy@cs.mcgill.ca (Yeo-Hoon BAE) (01/09/91)
Hi everyone, This may be a silly question, but I am puzzled with the type of memory chips used on various different computers. More specifically, I am comparing between the SIMMS/SIPPS used by 32 bit Amiga system against the 030 Macs or 386's. From what I know, they can get perfectly reasonable performance by using the normal 70/80ns 1x8 SIMMS which are CHEAP, but why the heck does all 32bit Amiga uses more expensive chips? Is it not possible to design them to use the standard SIMMS, like what 386's use ? A guy who owns Mac SE/30 claims that you can get 32bit fetches from memory by arranging the 1x8 SIMMS appropriately.... Any explanations would be appreciated. +-----------------------------------------------------------+-------------+ | Yeo-Hoon Bae tinyguy@homer.cs.mcgill.ca | Amiga /// | | Dept. Computer Science, McGill University, Canada | 2000 /// | |-----------------------------------------------------------| \\\/// | | Amiga2000 + 3MB + 104MB HD + KX-P1124 + Mit. DiamondScan | \XX/ | +-----------------------------------------------------------+-------------+
daveh@cbmvax.commodore.com (Dave Haynie) (01/10/91)
In article <1991Jan9.065738.2981@cs.mcgill.ca> tinyguy@cs.mcgill.ca (Yeo-Hoon BAE) writes: >Hi everyone, > This may be a silly question, but I am puzzled with > the type of memory chips used on various different > computers. More specifically, I am comparing between > the SIMMS/SIPPS used by 32 bit Amiga system against > the 030 Macs or 386's. From what I know, they can get > perfectly reasonable performance by using the normal > 70/80ns 1x8 SIMMS which are CHEAP, but why the heck > does all 32bit Amiga uses more expensive chips? Is it > not possible to design them to use the standard SIMMS, > like what 386's use ? There are several reasons to use the ZIP parts, as on the A3000 and the A2630. First of all, they don't cost any different from the manufacturer -- you get SIMMs cheaper from dealers than ZIPs because [a] there's so much competition amoung dealers for SIMMs, they can't mark them up much, and [b] you many be looking at the wrong dealers to buy your ZIP parts. There are technical reasons to use ZIPs. We want to ship a system with 1MB or 4MB of 32 bit memory. With the current A3000 arrangement, you can keep your 1MB on a 1MB system, moving it over to the Chip bus, and populate the Fast RAM bus with 1Meg x 4 ZIPs. We would have been OK with the 32 bit SIMMs (which are a standard), but they are harder to find than the ZIPs, since no one's using them in any quantity. The SIMM modules are taller than ZIPs, and would not left enough room for the A3000's Coprocessor Board, which sits directly over the memory array. The other problem is that most SIMMs, including the ones the Macs use, are Page-Mode. The A3000 needs Static Column memory to take full advantage of its memory design. Again, that's something you would not find in the average computer store, and where you did find it, it would be more expensive, because computer dealers know they can charge more for something that's harder to find. >| Yeo-Hoon Bae tinyguy@homer.cs.mcgill.ca | Amiga /// | -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "Don't worry, 'bout a thing. 'Cause every little thing, gonna be alright" -Bob Marley