jamii@xochitl.uucp (Jamii Corley) (04/13/89)
I'm confused about memory expansions for the Mac Plus, and SE. I've heard
the terms 'high-profile' and 'low-profile', as well as discussions of memory
speeds. Is high vs. low profile just a matter of how they're mounted? Can
one use either high or low profile SIMMS in a Mac Plus, but only low profile
in an SE?
I thought I remembered someone saying that the Plus took SIMMs with a
different speed (150 ns?) than the SE (120 ns), is this correct? Can a Plus
run with faster memory? 120ns? Can an SE run with slower memory?
I'd appreciate any light that people can shed for me.
Thanks,
Jaibobd@hpuxa.ircc.ohio-state.edu (Bob DeBula) (04/14/89)
As a general rule, you can use faster SIMMs (or chips) than are required by the machine, you cannot use slower (i.e. 150ns in place of 120ns). The low profile vs. high profile has to do with whether or not there is sufficient clearance to seat 'em in the socket. High profile SIMMs generally contain standard 1 Mb (or 256K as the case may be) DRAM chips soldered to the SIMM board. Low profile SIMMs generally contain the itty-bitty "surface mount" chips. This can be a *very* important point depending on the system you want to stick 'em in (i.e. "high profile" SIMMs can mean big trouble if the clearance is insufficient). I have not seen any situation where "low profile" weren't preferable to "high profile" (your mileage may vary depending on the buckazoids you wish to spend :-). I hope I got all this right! (As per usual I try my best, but I wouldn't take what I say as 100% defect free or invulnerable to misinterpretation ;-). -=- ------------------------------------------------------------------------------- Bob DeBula | Internet: debula-r@osu-20.ircc.ohio-state.edu The Ohio State University | Disclaimer: These are my views, not the U's
mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) (04/14/89)
In article <72@nisca.ircc.ohio-state.edu>, bobd@hpuxa.ircc.ohio-state.edu (Bob DeBula) writes: > As a general rule, you can use faster SIMMs (or chips) than are required by > the machine, you cannot use slower (i.e. 150ns in place of 120ns)... However, the SE for the most part comes with SIMMs that ARE faster than required. A standard SE needs 150ns SIMMs, but normally comes with 120ns SIMMs (some early SEs did come with 150ns SIMMs), apparently because of quantity discounts on the 120ns SIMMs (the same ones as used in a Mac II, IIx, and IIcx). To avoid confusion, I would say to only get SIMMs that are 120ns or faster. The slower ones may work now, but if you ever upgrade in the future... -Michael -- Michael Niehaus UUCP: <backbones>!{iuvax,pur-ee}!bsu-cs!mithomas Apple Student Rep ARPA: mithomas@bsu-cs.bsu.edu Ball State University AppleLink: ST0374 (from UUCP: st0374@applelink.apple.com)
lauac@mead.qal.berkeley.edu (Alexander Lau) (04/14/89)
In article <6760@bsu-cs.bsu.edu> mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) writes: >To avoid confusion, I would say to only get SIMMs that are 120ns or faster. >The slower ones may work now, but if you ever upgrade in the future... > >-Michael The rumor is that the 25 MHz stuff that Apple is putting out "real soon now" will require 100 ns chips, and the 33 MHz stuff will require 80 ns chips. But, of course, that's only a rumor. :-) --- Alex UUCP: {att,backbones}!ucbvax!qal.berkeley.edu!lauac INTERNET: lauac%qal.berkeley.edu@ucbvax.berkeley.edu FIDONET: Alex.Lau@bmug.fidonet.org (1:161/444)
mithomas@bsu-cs.bsu.edu (Michael Thomas Niehaus) (04/14/89)
In article <23084@agate.BERKELEY.EDU>, lauac@mead.qal.berkeley.edu (Alexander Lau) writes: > > The rumor is that the 25 MHz stuff that Apple is putting out "real > soon now" will require 100 ns chips, and the 33 MHz stuff will require > 80 ns chips. But, of course, that's only a rumor. :-) > > --- Alex This rumor seems very likely, since Apple has now started shipping their faster machines (SE/30 and IIx -- I don't know about the IIcx) with 100ns memory when they only need 120ns memory. When they do this, then they are buying the 100ns SIMMs in sufficient quantities that they are not outrageously expensive for the new machine... Also, I believe that the memory upgrade kits that you can buy from Apple (if you want to pay that much) are also 100ns SIMMs. Can you say stockpile :-> -Michael -- Michael Niehaus UUCP: <backbones>!{iuvax,pur-ee}!bsu-cs!mithomas Apple Student Rep ARPA: mithomas@bsu-cs.bsu.edu Ball State University AppleLink: ST0374 (from UUCP: st0374@applelink.apple.com)
smh@alux2.ATT.COM (S. Henning) (04/14/89)
In article <72@nisca.ircc.ohio-state.edu> (Bob DeBula) writes:
:
: High profile SIMMs generally contain standard 1 Mb (or 256K as the case may
: be) DRAM chips soldered to the SIMM board.
^^^^^ read DIPS not CHIPS.
: Low profile SIMMs generally contain the itty-bitty "surface mount" chips.
Read PACKAGES not CHIPS ^^^^^
Also know that the CMOS chips run much cooler and avoid the need for special
power supply considerations and special cooling.
A SIMM with CMOS chips in surface mount packages (low profile) is the
only configuration that is compatible with all Mac options. Any other
configuration requires certain restrictions.
By the way, the chip is a piece of semiconductor that is in a DIP or
surface mount package. A DIP is a dual-inline-package with leads that
are soldered through holes in the SIMM, and a surface mount package is
a very small package with J-shaped leads that are soldered on the
surface of the SIMM. Some surface mount packages are called J-leaded
and the J curves away from the package and others are called gull-winged
and the J curves under the package. All the ones I have seen on SIMMs
are gull-winged. Also, surface mount packages have leads on all 4 sides
while DIPS only have leads on 2 sides.
Cheers,
Steve Henning, AT&T Bell Labs, Reading, PA UUCP: att!alux2!smh
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