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Motorola 68851 PMMU discontinued

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Robert Vale

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Oct 19, 1989, 5:44:34 AM10/19/89
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Organization: The Vale Organization, Inc.
KeywordsMac II, PMMU, Motorola:

i
I just spoke with Bob Novis of Motorola Intra-company sales, and he told m that
Mototola has discontinued the MC 68851 Paged Memory Management Unit. This is the
chip thet Apple uses in the Mac II for virtual memory function. He further said that the last sale of these chips was on May 5, 1989 for a quantity of two to
a distributor. Currently he said, Motorola has 4 chips in stock and that they
are located in Tokyo, Japan. What is interesting about all this, besides th large amount
of Mac II owners who will not be able to upgrade, is that Notorola is still
mass producing the 68020 microprocessor. I wonder how you can get virtual memory out of that now without the PMMU? Oh, thre is no alternate supplier for the chip.

Thought yad like to know.....

e
Robert Vale ---> va...@arrakis.nevada.edu INTERNET
(702) 735 - 6139 Voice

Saiid Paryavi

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Oct 19, 1989, 10:33:18 AM10/19/89
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In article <9...@unsvax.NEVADA.EDU> va...@arrakis.nevada.edu (Robert Vale) writes:
>Organization: The Vale Organization, Inc.
>KeywordsMac II, PMMU, Motorola:
>
>i
>I just spoke with Bob Novis of Motorola Intra-company sales, and he told m that
>Mototola has discontinued the MC 68851 Paged Memory Management Unit. This is the
>chip thet Apple uses in the Mac II for virtual memory function. He further said that the last sale of these chips was on May 5, 1989 for a quantity of two to
>a distributor. Currently he said, Motorola has 4 chips in stock and that they
>are located in Tokyo, Japan. What is interesting about all this, besides th large amount
>of Mac II owners who will not be able to upgrade, is that Notorola is still
>mass producing the 68020 microprocessor. I wonder how you can get virtual memory out of that now without the PMMU? Oh, thre is no alternate supplier for the chip.

I just spoke to the Motorola distributor in Kansas City and they said they
could supply as many PMMUs as I liked. They even game me some quantity
discount prices.


--
Saiid Paryavi Computer Science Dept.
Internet: par...@harris.cis.ksu.edu Nichols Hall
BITNET: par...@ksuvax1.bitnet Kansas State University
UUCP: {rutgers, texbell}!ksuvax1!harry!paryavi Manhattan, KS 66506

Ragnar Sundblad

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Oct 21, 1989, 3:31:15 PM10/21/89
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In article <9...@unsvax.NEVADA.EDU> va...@arrakis.nevada.edu (Robert Vale) writes:
>Mototola has discontinued the MC 68851 Paged Memory Management Unit.

I suppose he meant the 68451 MMU, which I don't think is one of their
best-sellers. ;-)
I find it hard to believe they will stop producing the 68851 PMMU.

Tim Maroney

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Oct 21, 1989, 5:39:50 PM10/21/89
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In article <9...@unsvax.NEVADA.EDU> va...@arrakis.nevada.edu (Robert Vale) writes:
>I just spoke with Bob Novis of Motorola Intra-company sales, and he told m that
>Mototola has discontinued the MC 68851 Paged Memory Management Unit.
>This is the
>chip thet Apple uses in the Mac II for virtual memory function. He further
>said that the last sale of these chips was on May 5, 1989 for a quantity of
>two to a distributor. Currently he said, Motorola has 4 chips in stock and
>that they are located in Tokyo, Japan.

In article <41...@deimos.cis.ksu.edu> par...@harris.cis.ksu.edu (Saiid Paryavi)
writes:


>I just spoke to the Motorola distributor in Kansas City and they said they
>could supply as many PMMUs as I liked. They even game me some quantity
>discount prices.

Perhaps Vale was confusing the 68851 and the older 68451 documented in
an appendix to the old 68000 manual. The 68451 was indeed a turkey
chip and I would be very unsurprised if it were discontinued. It seems
awfully unlikely that the 68851 would be discontinued with the 68020
still a hot seller, and it is inconceivable that Motorola would have
received *no* orders for the 68851 in the last six months.
--
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, t...@toad.com

"When the writer becomes the center of his attention, he becomes a nudnik.
And a nudnik who believes he's profound is even worse than just a plain
nudnik." -- Isaac Bashevis Singer

Phil Ronzone

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Oct 23, 1989, 12:24:55 PM10/23/89
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In article <9...@unsvax.NEVADA.EDU> va...@arrakis.nevada.edu (Robert Vale) writes:


Aya ya ya ---

Well, I've heard that it isn't being made because the same line is being
used to make more 68030's.

Well, I called my local distributor and yep, they have none in stock,
and if they did, they'd go for $350.

Anyway - I have four left from a group buy.
If anybody wants one, there are $280 each or two for $500.
Shipped insured next day delivery.

You don't need a PMMU for your Mac II UNLESS you want to
run A/UX or System 7.0 or the virtual memory init.


-------------------------------------------------------------------------------
Phil Ronzone Manager Secure UNIX p...@sgi.COM {decwrl,sun}!sgi!pkr
Silicon Graphics, Inc. "I never vote, it only encourages 'em ..."
-------------------------------------------------------------------------------

Jeff Wasilko

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Oct 24, 1989, 12:50:05 AM10/24/89
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Is Sun still shipping Sun 3/60s?

I would assume that they need PMMUS to run unix...

Phil Ronzone

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Oct 24, 1989, 1:51:01 PM10/24/89
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In article <33...@netcom.UUCP> was...@netcom.UUCP (Jeff Wasilko) writes:
>
>Is Sun still shipping Sun 3/60s?
>
>I would assume that they need PMMUS to run unix...

No, the SUN 3 uses a discrete logic MMU. A major drawback is that it was
expensive if you had to unload a context. A fun thing to do with A/UX was
to set up a benchmark involving 30 processes passing short messages to
each other. The context switch load/unload on the SUN would kill it in
comparision with any PMMU based system.

Dave Haynie

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Oct 26, 1989, 5:10:14 PM10/26/89
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in article <10...@odin.SGI.COM>, p...@maddog.sgi.com (Phil Ronzone) says:

> In article <33...@netcom.UUCP> was...@netcom.UUCP (Jeff Wasilko) writes:

>>Is Sun still shipping Sun 3/60s?
>>I would assume that they need PMMUS to run unix...

> No, the SUN 3 uses a discrete logic MMU.

So do the Apollos, far as I know (though I've never looked at the newer '020
based desktop models). The Amiga 2500 includes the 68851, and I'd certainly
think other machines would too. Though Motorola was so late with '851, it's
not surprising that many '020 machines use hand-made MMUs. At Commmodore, we
had even started working on our own VLSI MMU, but Motorola came though just
in time. So while I'd be surprised to believe Moto's cancelled the '851, the
cost factors are already in the favor of the '030, and replacing an '020/'851
with an '030 is a lazy afternoon's work in most systems.

> Phil Ronzone Manager Secure UNIX p...@sgi.COM {decwrl,sun}!sgi!pkr

--
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
{uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy
Too much of everything is just enough

Tom Fitzsimmons

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Oct 28, 1989, 3:57:10 PM10/28/89
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Any one have a 68851??? I need on for my Radius board!
Call me voice if you have one for sale....(206) 889-9871 or CrashMail
343/49..........Thanks Tom Fitzsimmons

--
Tom Fitzsimmons via cmhGate - Net 226 fido<=>uucp gateway Col, OH
UUCP: ...!osu-cis!n8emr!cmhgate!343!49!Tom.Fitzsimmons
INET: Tom.Fit...@f49.n343.z1.FIDONET.ORG

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