I'm almost positive that there was something like this on the IIfx in reguards to RAM. I don't know why, but the IIfx was an oddball of sorts. The black SCSI terminator, the quirky RAM. I have a dead one at my warehouse (yes, I got a smaller place and had to store all but one of my old Macs--a Classic is the only one with me) and I will make an effort to check the RAM out on it when I go in a few weeks. I might put it side by side with my other II series (I have a IIsi, a II, and an SE/30 which is like a IIx) just to see.
Scott --- [EMAIL PROTECTED] wrote: > on 8/31/05 4:27 PM, John Niven at > [EMAIL PROTECTED] wrote: > > > On Aug 31, 2005, at 11:44 AM, Jeff Walther wrote: > >> The pinout shows a separate data_in and data_out > pin for each bit of > >> the SIMM. In other words, it's an eight bit > SIMM, but instead of > >> simply having eight data pins Data[0:7] it has > eight Data_In[0:7] and > >> eight Data_Out[0:7] pins. > > > > The "by one bit" DRAMs had separate input and > output pins. Most users > > just tied them together and hooked them to a > bi-directional bus. I > > haven't looked into this, but I always assumed > that what the IIfx did > > was keep the In and Out busses separate so that > the timing operations > > could be overlapped thus speeding up memory > operations. > > > >> That could imply that the IIfx SIMM requires > bizarre dual data ported > >> chips, but the chip examples I've identified > (thanks Bob) seem to be > >> normal DRAM chips. > > > > I assume the mother board has the "bizarre dual > data ported chips" so > > the SIMMs are unique in NOT hooking the In and Out > pins together :-) > > > > > > John > > > Didn't IIfx RAM's have nine bits for error > detection? I seem to remember > that there was something different about them and > the RAM for a IIfx was > unique to that Mac. All other Macs of that vintage > had interchangeable RAM. > > r > > > -- > Vintage Macs is sponsored by <http://lowendmac.com/> > and... > > Small Dog Electronics http://www.smalldog.com > | Enter To Win A | > -- Canon PowerShot Digital Cameras start at $299 > | Free iBook! | > > Support Low End Mac > <http://lowendmac.com/lists/support.html> > > Vintage Macs list info: > <http://lowendmac.com/lists/vintagemacs.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/vintage.macs%40mail.maclaunch.com/> > > iPod Accessories for Less > at 1-800-iPOD.COM > Fast Delivery, Low Price, Good Deal > www.1800ipod.com > ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs -- Vintage Macs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Vintage Macs list info: <http://lowendmac.com/lists/vintagemacs.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/vintage.macs%40mail.maclaunch.com/> iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com
