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From: dennisg@sdcrdcf.UUCP (Dennis Griesser)
Newsgroups: net.micro.mac
Subject: Re: Macintosh Plus: why not 12 Mhz
Message-ID: <2584@sdcrdcf.UUCP>
Date: Thu, 16-Jan-86 14:40:38 EST
Article-I.D.: sdcrdcf.2584
Posted: Thu Jan 16 14:40:38 1986
Date-Received: Sat, 18-Jan-86 08:21:14 EST
References: <593@harvard.UUCP>
Reply-To: dennisg@sdcrdcf.UUCP (Dennis Griesser)
Organization: System Development Corporation R&D, Santa Monica
Lines: 34

In reply to <593@harvard.UUCP> matthews@harvard.UUCP (Jim Matthews):

>	I got a peek at a Mac Plus yesterday, and it's pretty much
>what the rumors have projected: an old mac with new ROM, a double-sided
>drive, 1 Meg RAM, and a SCSI interface.  The modem and printer ports
>are little round connectors, making room for the SCSI port.

There had been rumors to this effect on the net.  Now they seem to be verified.
Apple has made all of our cables obsolete!  This is especially sad for the
special interfaces that clamp to the back of the Mac (like Assimilation's MIDI).

>                                                             The only
>thing I found surprising was the way they fit 1 Meg onto the motherboard.
>The RAM chips are on little strips of pc board (four of them, with 8 chips
>each) which are mounted at a 45 degree angle to the main digital board.   

The strips are called "SIP"s, for Single In-line Package.  They have been
available for a long time.  Various foreign and domestic companies offer them,
including TI.  You can usually get them with 4, 8, or 9 RAMs on a strip.  One
company puts 18 of them on, nine on each side.

>	My one dissapointment was that they stuck with the 8 Mhz 68000,
>instead of using the 12 Mhz model (which is used in the Laserwriter).

Don't forget that memory access is split between the CPU, video, and sound/IWM
systems.  Each area has its own time slots in the overall picture.  You DO need
faster RAM.  You would probably end up doubling the CPU clock and cramming two
CPU cycles into the current one, and leave the other stuff alone.  I suppose
that it is not a big problem, but just a bit more than Apple wanted to tackle
this time.  Hmmm, if the memory is twice as fast, you could speed up the video
part too and double the horizontal resolution.  But we need to keep the pixels
square...
-- 
[Standard disclaimers apply.]