Random Tricks and Musings

The 8x51 series *has* internal ROM, even the 8051. The 8031/8032 are allegedly "ROMless" versions of the 8x51/52.

What that means to designers/hobbiests is, e.g.: 

You can design for an 8031, with an external ROM, then drop-in any old 8x51, even if its (OTP, mask, etc.) ROM was programmed with code from an entirely different product, or buggy, or whatever.
Find some old 8x51 in some old piece of trash, think it's worthless because it's already been programmed...? Tie one pin to a voltage rail and use it as an 8031 in your own project.

What that probably meant from Intel's perspective:

"Hey, a customer ordered a bunch of preprogrammed 8051's, but discovered a bug before we shipped" and/or "We got a batch of 8051's with flaky ROMs" and "we're sitting on 1000's of otherwise useless 8051's. What should we do with them?" "Remarket them as ROMless 8031's, and let the new customer supply their own ROM chip!"

Forward-thinking, reusability, reduction of eWaste...

And, in this new era of old paper datasheets now scanned and uploaded as pdfs (as opposed to my earlier experience where pdfs only existed for products designed in the pdf-era (THANK YOU to those who take the time and provide that effort!)), I've discovered that many previously zero-search-result ICs on old PCBs scavenged from VCRs, CD players, TVs, Stereo Components, and whatnot, now have full-on datasheets detailed down to instruction-sets and hex operands... 

And many of those, similar to the 8051, have a pin which can be tied to a voltage rail to disable the internal mask-ROM, enabling them, like the 8031, to run off an external ROM.

Wow! SO MANY uC designers, of so many various architectures, even 4-bit, considered this worthwhile! And even if it was purely because they wanted to sell otherwise defective/wrongly-programmed uCs, it *still* benefits the likes of the customer and even the alleged us, that are hardware hackers.

I dunno, I thought it was darn-relevant in the "chip shortage era."

[Inspired by the lack of response to my comment at https://hackaday.com/2022/12/01/ask-hackaday-when-it-comes-to-processors-how-far-back-can-you-go/ and the fact it seems to be blocking my adding the above as a clarification-reply.

Fact is, I've been meaning to document my box full of scavenged PCBs with such uCs, and maybe even turn each into a "NOPulator"]

...

Oh, it finally appeared there, twice, numerous hours later. Heh.

I even got a response suggesting looking into Collapse OS: http://collapseos.org/

(Very Intriguing).

...

Lots more thoughts and My Collection, now over at:

#Repurposing OTP/mask-ROM microcontrollers 

I wonder how many folk training AI have never even trained a dog to shake.

What IS The Speed of Light Squared?

What IS Distance Squared Over Time Squared... ?

What is Time Squared?!

Dunno, BUT:

Well, Acceleration is Distance Over Time Squared...

And Distance Squared is Area

So might Speed Squared be The Acceleration Of Area?

...

"The Acceleration of Area Is Constant" ?

If you were to release a ball down a ramp, its acceleration would be constant, (assuming constant gravity and constant slope).

If you drop a rock in a pond, the ripples propagate outward at a constant speed along the radius... But, interestingly, the Circumference of the ripple has a constant "acceleration" (distance over time squared)

If you were to create a "ripple" in three-D space, say by exploding some TNT in midair, the sound of the explosion would propagate at a constant speed radially in all directions, at the speed of sound... The surface-area of that 3D "ripple" would have a constant acceleration.

So, if all the energy in some mass were released instantaneously, it would create a spherical wavefront whose surface-area would "accelerate" at a constant rate.

E= MC^2

So, then... Energy is usually electromagnetic, right? And ripples in  electromagnetic fields travel at the speed of light...

So E=MC^2 basically says that if you were to instantaneously release all the energy that a mass *can* contain into a burst of electromagnetic energy, then that energy would propagate as an electromagnetic wave-front which has a constant "acceleration of surface area". I.E. a /sphere/ (?)

...

Now, if we think of it this way, and we change our units of time and speed from meters and seconds to something instead related to the propagation of this wavefront, we'll find that the "constant acceleration of surface-area" (i.e. C^2) Is Directly Related to Pi^2, and thus the speed of light (radially) is in fact an integer constant times Pi. (?!)

...

Musings not yet verified.

Note that I later found an article about a  relationship between Pi and C, which derives it through the half-period of a pendulum. Unfortunately, I'm not sure the math works-out, due to the fact that a pendulum's period is not /exactly/ as stated, but only /very close/, under some conditions. However, the fact is those /specific/ conditions seem to come /very close/ to equating C to Pi, in a very similar way as my wavefront-propagation theory does.

...

So, what are the implications?

Dunno, haven't had time to really look into it, yet.

However, one path seems to suggest that gravity, too, is directly related to C^2 (and thus Pi^2), which makes sense if considering, again, the idea of the surface-area of a wavefront's propagation. 

Imagine a brief "pulse" of gravity as the opposite of an electromagnetic explosion... An implosion(?). Its wavefront (pulled into its center, rather than extending away from it) would have a constant acceleration (of surface-area). 

So, now, imagine a constant flow of such energy, much like a constantly-lit lightbulb...

...

I dunno where it goes!

Here's a weird thought just popped-up...

Gravity doesn't /do/ anything, unless there's another object involved. So, until another object comes into the path of its (impulse) "wavefront," that wavefront exists everywhere on the sperical surface. But, when an object comes into its path, does that spherical surface "collapse" onto that object? Much like they suggest a photon may propagate outward in every direction spherically /until/ it hits something? At which point that sphere collapses onto that object, much like an expanding bubble in bubblegum "rubberbands" (spherically!) back to one's face?

...

hmmm...

Think of Conductivity, instead.

Two parallel conductors will conduct better than one...

ConductivityTotal 
     = Conductivity(R1)
        + Conductivity(R2)
        + Conductivity(R3)
        + ....

Conductivity of a resistor = 1 / Resistance

WAY easier to remember, intuit, (and calculate?) than 1/Rt = 1/R1 + 1/R2 + 1/R3 ...