Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.arch Subject: Re: 1st 64 Megabit DRAM Message-ID: <12646@cbmvax.commodore.com> Date: 13 Jun 90 18:12:34 GMT References: <16348@smunews.UUCP> <1990Jun11.032747.15462@agate.berkeley.edu> <511@dg.dg.com> <57316@bbn.BBN.COM> <31499@ut-emx.UUCP> <90Jun12.183151edt.2787@ois.db.toronto.edu> Reply-To: daveh@cbmvax (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 32 In article <90Jun12.183151edt.2787@ois.db.toronto.edu> jonah@db.toronto.edu (Jeff Lee) writes: >hcobb@walt.cc.utexas.edu (Henry J. Cobb) writes: >Can anyone with a hardware design background say what the problem is >with wider memory chips (BESIDES having to change the packaging/pinout >of the memory chips). I think the issue so far has just been density. Before the 1 Meg density parts came along, you rarely found a DRAM that wasn't a simple 1 bit part. Certainly there were 64k x 4 parts in the 256K density, but they weren't very popular. With the 1 Meg and 4 Meg parts, the 4 bit packages are more popular, since that amounts to a reasonable chunk of memory -- 512K on a 16 bit bus or 1 Meg on a 32 bit bus with 1 Meg density parts. You probably don't want less for most applications, and going to an 8 or 16 bit package would increase board space for the same amount of memory. There are already specifications for 8 bit DRAMs, and I wouldn't be surprised to see these become popular when 16M DRAM gets reasonable. The other issue is of course the standard packaging; I can build a board today for 256k x 4 parts which can easily support the 1 Meg x 4 parts, since they use compatible packages. This is much less an issue if you're using memory modules, since the PCB of the module sorts out the actual packaging issues for you. But you're not going to have 4 or 16 Meg x 4 parts in a compatible package anyway, so I imagine a new basic DRAM part size will become the standard one when these parts are out in force. >j. -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy "I have been given the freedom to do as I see fit" -REM