Date: Fri, 24 Oct 2003 16:02:40 -0700 From: Gamba <[EMAIL PROTECTED]> Subject: Re: IIfx RAM, was: SE/30 Upgrade ROM?
So why all the pins on the IIfx memory? Does anyone know? Jeff Walther
I think I found the answer. Reading from the May 1990 issue of Macworld magazine: "The SIMMs themselves are different too They contain separate input and output lines, which work together with the IIfx's custom memory controller chip to allow data to be written to and from the memory simultaneously".
Wow, now that's interesting. I was browsing some datasheets of memory components from Oki Semi that I have on my hard drive and one of the DRAM chips I looked at had separate data in and data out lines, which puzzled me, as I had never seen a SIMM with separate data in and data out pins. I guess that model of chip was for use on something like the IIfx SIMM.
MSM511000C or CL is 1M X 1. MSM514100D or DL is 4M X 1. They both have separate Data in and Data out pins. Browsing some Austin Semiconductor data sheets I have, I find that all the examples of X 1 chips have separate data-in and data-out. I wonder if all X 1 chips have separate Data In and Data Out. On 30 pin SIMMs, they would probably just tie them together and on the 64 pin SIMM they could route them out separately.
More to the point, I've never seen a 16 MB IIfx SIMM. I don't have a IIfx, but that doesn't stop me from wondering if it's possible to build a 16 MB SIMM for the IIfx. If the chips on a 16 MB 30 pin SIMM have separate data-in and data-out pins, then it might be as easy as moving the chips from a standard 16 MB SIMM to a 4 MB IIfx SIMM and maybe run a few wires, if an extra address line needs to be hooked up or something.
Jeff Walther
-- Compact Macs is sponsored by <http://lowendmac.com/>.
Support Low End Mac <http://lowendmac.com/lists/support.html>
Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/>
---------------------------------------------------------------
The Think Different Store
http://www.ThinkDifferentStore.com ---------------------------------------------------------------
