[Coco] ceramics ...
jdaggett at gate.net
jdaggett at gate.net
Fri Sep 3 22:22:40 EDT 2004
Mark
Speed ratings on digital ICs are made based on operating voltage and package
style. All of this is taken into consideration with the package's ability to keep the die
inside cool enough to operate within design parameters. If you cryo cool a 6809 you
can problably run it up to about 9 to 10 MHz before the NMOS process of that
period breaks down due mainly to the nmos transisitor geometries and interanal
capacitances limit the propogation delay through the processor.
The temperature of the silicon chip inside the package is the limiting parameter to
speed. CMOS ICs draw their current when switching. Therefore the faster they
switch the greater the RMS current is. The greater the RMS current is the hotter the
silicon gets.
It is heat that causes early failure to the silicon and reliability problems. Heat is
directly proportional to clock speed and inversely proportional to the ability of the
package to remove the heat from the silicon chip. As I have stated before, keep the
silicon cool and it will operate for about 20 yrs. Most ICs made will eventually fail
even operated within al parameters. This is due to the physics and the chemistry of
making ICs. There are impurities that eventually cause ICs to fail. Heat agrivates
this process.
The GIME has to operate with the 28 .636 MHz crystal to maintain the fixed diveder
ratios to generate timing. I have no need to change that or desire to.
james
On 3 Sep 2004 at 15:23, mmarlett at isd.net wrote:
From: mmarlett at isd.net
To: coco at maltedmedia.com
Date sent: Fri, 3 Sep 2004 15:23:43 -0500
Subject: Re: [Coco] ceramics ...
Send reply to: mmarlett at isd.net,
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> james,
>
> Common knowledge for most. Kind of like telling my Son that just
> because the RPM gauge runs in the RED doesn't mean the engine will run
> forever there.
>
> The GIME, TCC1014A....Same thing here, sure you can run it faster. I
> have modified the XTAL to 32MHZ for a true 2MHZ and adjusted the
> internals of my monitor to compensate. My experience has been that the
> GIME/motherboard or whatever becomes unstable. This is my personal
> experience. Roll them back and they work just fine. All my mod'd
> machines have all been returned to stock speeds due to reliability
> reasons.
>
> What overclocking have you done to the GIME and what were your
> results? Please provide revision information, if relevant to your test
> cases.
>
> Mark
>
>
> >Kevin/Mark
> >
> >Digital IC's speed specification is the maximum speed for a device
> >such as
> there
> >will guarenteed 100% compliance to the spefications of the IC. This
> >is by
> far not
> >the fastest the IC can run. Speed is often determined at die probe
> >and by
> which
> >package the die is placed in. Several parameters have to be taken in.
> >Of
> one of
> >the primary parameters of concern is heat. While the package
> >temperature maybe warm, but the actual die temperature can be as much
> >a twice the
> outside
> >package temperature. The main goal is to keep the die temperature
> >below
> 150
> >degrees C. Heat is the ultimate killer of semiconductors. Above 150 C
> >the physics of the semiconductor breaks down and all kinds of nasty
> >things
> happen.
> >Eventually, in MOS devices, the channels that allow electron mobility
> fail. Now
> >you have a piece of silican that is no longer functioning.
> >
> >Kevin you are right in one aspect, the ceramic parts can operate at
> >higher
> clock
> >speeds than say the common injection molded palstic parts. Ceramic
> conducts
> >heat better the plastic.
> >
> >The second parameter that affects digital IC speed is the basic
> >geometry
> of the
> >transistors used to make the gates and the fabrication process, NMOS,
> HMOS,
> >CMOS bi-CMOS and so forth. Smaller geometry transistors have higher
> >gain bandwidth product and thus smaller propogation delays between
> >the gate and
>
> >drain.
> >
> >If you can heat sink the pakage sufficiently a digital IC can be
> >clocked
> as fast as
> >it can accept it. That generally is when the pin to pin propogation
> >delay
> is slower
> >than the clocked data. Generally speeking, the propogation delay
> >through
> the IC
> >should not be more than 25 to 50% of the clock cycle.
> >
> >
> >The GIME chip will handle higher clock speeds. T he problem is that
> >to get
>
> >proper HSYNC and VSYNC and color info correct it must be clocked at
> >the perscribed frequency of 28.6363 MHz. Faster or slower will change
> >internal
>
> >timings that allow for proper NTSC and CG A video modes.
> >
> >james
> >On 3 Sep 2004 at 4:15, Mark Marlette wrote:
> >
> >Date sent: Fri, 03 Sep 2004 04:15:12 -0500
> >To: CoCoList for Color Computer Enthusiasts
> ><coco at maltedmedia.com>
> >From: Mark Marlette <mmarlett at isd.net>
> >Subject: Re: [Coco] ceramics ...
> >Send reply to: 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>
> >
> >> 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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