[rescue] Perverse Question

Dave McGuire mcguire at neurotica.com
Sun Jun 15 17:49:02 CDT 2003

On Sunday, June 15, 2003, at 06:26 PM, Carl R. Friend wrote:
>    I know for a fact that some of the machines under my charge
> at work run frighteningly hot (better than a 40 degree rise from
> air intake to exhaust) and I'm sure won't have terribly long
> lives.  This does not make me happy.

   Wow...40 degrees?!

>>   [Making a chip smaller is] the biggest problem.  To get more 
>> density,
>> you need smaller wires, and the wires are now so small they can barely
>> carry the [miniscule] current.
>    Hence copper rather aluminium traces.

   ...which will only go so far.  Copper chips aren't all that new 

>    From waht I'm given to understand, one hell of a lot of the power
> is consumed (and, correspondingly, heat produced)  just by the clock
> circuitry.  These boys could learn something from the async-logic
> "of old".

   I seem to recall having heard that parts of the P-IV are 
asynchronous, but I'm not sure; can anyone comment on this?  I'd like 
to find out once and for all.

>    Of course now they're resorting to tricks to get the clock speed up
> for marketing reasons rather than technical ones.

   Yup.  Sleazy.

>    I don't regard the genesis of the x86 line to lie with the 8080 and
> its progeny.

   But it certainly does.  We can ignore that, though, and the point 
still stands...see below.

>   When was the first 8086 made?  I think it's more
> contemporaneous to the VAX than older.  The original VAX, the 11/780
> debuted in 1977.

   The 11/780 and the 8086 both shipped in 1978, though I don't know the 
months offhand.  The 8086 is a rather direct extension of the 8080/8085 
architecture...The VAX shares some architectural features with its most 
direct predecessor, the PDP-11, but nowhere near enough to be called an 
extension of the architecture.

   Even at the hardware/implementation level...a complete 8080-based CPU 
consists of three chips: the 8080 CPU, the 8224 clock generator, and 
the 8228 system controller and bus driver.  A complete 8086-based 
system consists of an 8086 CPU, an 8284 clock generator, and an 8288 
system controller and bus driver (the latter of which is admittedly 
optional for the 8086).  While they're not binary-compatible, 8080 vs. 
8086 assembly code is nearly directly upward compatible.


Dave McGuire             "I've grown hair again, just
St. Petersburg, FL           for the occasion."       -Doc Shipley

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