[Coco] ceramics ...

jdaggett at gate.net jdaggett at gate.net
Sun Sep 5 01:48:49 EDT 2004


Mark

Heat, Heat, Heat

Also Mark the design that we used the 6809 in was to transmit digital data stream. 
We needed to boost the transmit speed and found that raiseing the clock speed on 
a 68B09 to 12 MHz (3 MHZ buss) from 8MHz (2 MHZ buss) allowed us to do that. 
Otherwise we needed to redesign the whole test equiptment. We used about 1000 
of them worldwide. The cycle time and cost to redesign them with a new processor 
versus taking the risk of increase buss speed was a calcualted risk but a reasonable 
risk. A few phone calls to the right people and the right questions were answered 
and we undertook the course of action that we did. It worked. Will it work on 
everything? No. But we did not just go out and drop in a new crystal and prayed.   

Injection molded palstic package has a thermal resistance of about 100  degrees C 
per watt. Ceramic is half that. Ceramic will take the heat off the die faster than 
plastic. Injection molded plastic parts are about 5 cents per pin to package. Ceramic 
now are about 12 cents per pin. Ball grid array is now about 2 cents per pin. The 
older Pentium IIs that used socket 7 package have more cost in the package than it 
takes to make the die. The die for a PII is in the area of $20 and the package is in 
the area of $40. With the P3s and the P4s the package costs were prohibitive and 
besides at those clock speeds the ceramic package was to inefficient to pull heat off 
the part. Now the heat sink litterally sits on the backside of the die. 

Now that I said that, I also should have stated this. ICs undergo changes during their 
life cycles.  One is almost always a die shrink. That is where they cram more ICs on 
a wafer to get more parts. Often first run parts are limited and may not have all the 
benefits of faster speed performance from later production lots. 

Manufacturers do things to reduce cost. Die shrinks and package changes are some 
of a few. Many times steps to reduce cost also improve performance. If the origianl 
part is speced for a certain speed and a cost reduction actually improves the speed 
performance, the origianl spec is never upgraded. Sometimes the improved speed 
is never mentioned and only known internally. Sometimes the cost reduced part is 
reissued  under a new part number. Also the part maybe issued under a new speed 
grade. 

The 68K parts I believe originally were 8 MHz parts. Later die changes have allowed 
the parts to operate faster. So Motorola introduced new speed grades. They did not 
have to. 8MHz parts made under the newer process may operate at higher speeds 
but the current drain will be higher than of a 12MHZ speed graded part. That is what 
you take a risk in. Higher average current drain means more heat. More heat means 
certain death. 

james 

On 4 Sep 2004 at 7:27, Mark Marlette wrote:

Date sent:      	Sat, 04 Sep 2004 07:27:43 -0500
To:             	CoCoList for Color Computer Enthusiasts 
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From:           	Mark Marlette <mmarlett at isd.net>
Subject:        	Re: [Coco] ceramics ...
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> At 9/3/2004 10:25 PM -0400, you wrote:
> 
> james,
> 
> Again I'm sure it is possible but why? Buy the rated chip and operate
> it as it was designed. Not like you can't purchase one at that speed.
> A different story when you want to operate a 2MHZ part at 12MHZ, you
> have no options, so you do it, take the risk.
> 
> My experience has been, run at rated or slightly higher. Make 25%+
> increases and look out.
> 
> Why do you think that the manufacture rates the chip as they do? May
> be we should forward this to them so that they can reevaluate how they
> rate their IC's. They could charge more $$$$ for them. Why make/sell a
> 16MHZ part when the consumer can use a 8MHZ part and a heat sink?
> 
> mark
> 
> 
> 
> >Mark
> >
> >We used 68B09's at clock speeds of 12 MHz, 3 MHz buss speed
> >24/7 for months on end. Had little fail ure from that.
> >
> >Yes it is quite possible to operate an 8 MHz 68K at 14 MHz. Again it
> >may be necessary to heat sink the chip though.
> >
> >james
> >
> >
> >
> >On 3 Sep 2004 at 15:36, mmarlett at isd.net wrote:
> >
> >From:                   mmarlett at isd.net
> >To:                     coco at maltedmedia.com
> >Date sent:              Fri, 3 Sep 2004 15:36:12 -0500
> >Subject:                Re: [Coco] ceramics ...
> >Send reply to:          mmarlett at isd.net,
> >         CoCoList for Color Computer Enthusiasts
> ><coco at maltedmedia.com>
> >         <mailto:coco-
> >request at maltedmedia.com?subject=unsubscribe>
> >         <mailto:coco-
> >request at maltedmedia.com?subject=subscribe>
> >
> > > Kevin,
> > >
> > > I doubt that the Motorola parts will run at 14+MHZ if they are
> > > spec'd at 8MHZ.
> > >
> > > I remember your project(s), not that I don't care for them. Just
> > > not for me. I have done what you are trying to do and it is not a
> > > project to start on. Walk before you can run. That is all. I'm all
> > > for as many CoCo projects as people will do. GREAT machine to
> > > learn from. The board is only a small part of the project. When I
> > > get to that part, I know I'm very close to being done. Most of the
> > > work is done in the homework and design stage. Follow the layout
> > > rules, terminate, impedance match and it will work as designed.
> > >
> > > Mark
> > > Cloud-9
> > >
> > >
> > >
> > >
> > >
> > >
> > > >Mark,
> > > >
> > > >     The parts are speced at 8.
> > > >
> > > >     I already told you about the project idea. I don't think you
> > > >     liked
> > > >it. "CPU Paks" I would love to have a program pak with a 68000,
> > > >or an 80186, or a TI9900, or a 6502, or ... . I have no idea how
> > > >to do the board. Any suggestions.
> > > >
> > > >     And of course without a job none of this is going anywhere.
> > > >
> > > >                                   kevin
> > > >
> > > >Mark Marlette wrote:
> > > >> At 9/2/2004 09:04 PM -0700, you wrote:
> > > >>
> > > >> Kevin,
> > > >>
> > > >> Most parts have a designed clock that they were certified at
> > > >> and assigned when they were tested at their manufactured date.
> > > >> What are those clock speeds of the said chips? Seems to me to
> > > >> be a data book look
> > >
> > > >> up process. If theory doesn't work for you then just hook them
> > > >> up and try them out at the speed you want them to run. A bit of
> > > >> work since they
> > >
> > > >> are just chips and require a bit of work to connect up and
> > > >> test. Let us know what you find out though. Have some plan(s)
> > > >> for a new CoCo project here?
> > > >>
> > > >> Mark
> > > >> Cloud-9
> > > >>
> > > >>
> > > >>> Hi,
> > > >>>
> > > >>>         No hardware. Just a pair of chips. So the question
> > > >>>         refers to
> > > >>> them. Think they would run at 14.3181818?
> > > >>>
> > > >>>                                   kevin
> > > >>>
> > > >>> Mark Marlette wrote:
> > > >>>
> > > >>>> At 9/2/2004 11:57 AM -0700, you wrote:
> > > >>>> Kevin,
> > > >>>> Overclocking is generally not a good thing to do but it
> > > >>>> depends what you are trying to do. For instance, overclocking
> > > >>>> the CoCo3 is not a good thing due to the GIME. Can you tell
> > > >>>> us a bit more about the hardware that these CPUs are
> > > >>>> connected to? Regards, Mark Cloud-9
> > > >>>>
> > > >>>>> Hi,
> > > >>>>>
> > > >>>>>         I have a 68010 and a 68008. They are both 8s. Any
> > > >>>>> thoughts as to how high they could be SAFELY overclocked?
> > > >>>>> The plain 6809e in my deuce seems to run fine at 1.7 for
> > > >>>>> extended periods. But it does have a heat sink.
> > > >>>>>
> > > >>>>>                                   kevin
> > > >>>>>
> > > >>>>> Stephen H. Fischer wrote:
> > > >>>>>
> > > >>>>>> Hi,
> > > >>>>>> I thought I had one, but it is a 6800. I found a 6820 and a
> > > >>>>>> 8008.
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>>
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