Do Small-RAM Devices Have a Future? (CC 25th Anniversary Preview)

What does the future hold for small-RAM microcontrollers? Will there be any reason to put up with the constraints of parts that have little RAM, no floating point, and 8-bit registers? The answer matters to engineers who have spent years programming small-RAM MCUs. It also matters to designers who are hoping to keep their skills relevant as their careers progress in the 21st century.

In the upcoming Circuit Cellar 25th Anniversary Issue—which is slated for publication in early 2013—University of Utah professor John Regehr shares his thoughts on the future of small-RAM devices. He writes:

For the last several decades, the role of small-RAM microcontrollers has been clear: they are used to perform fixed (though sometimes very sophisticated) functionality in environments where cost, power consumption, and size need to be minimized. They exploit the low marginal cost of additional transistors to integrate volatile RAM, nonvolatile RAM, and numerous peripherals into the same package as the processor core, providing a huge amount of functionality in a small, cheap package. Something that is less clear is the future of small-RAM microcontrollers. The same fabrication economics that make it possible to put numerous peripherals on a single die also permit RAM to be added at little cost. This was brought home to me recently when I started using Raspberry Pi boards in my embedded software class at the University of Utah. These cost $25 to $35 and run a full-sized Linux distribution including GCC, X Windows, Python, and everything else—all on a system-on-chip with 256 MB of RAM that probably costs a few dollars in quantity.

We might ask: Given that it is already the case that a Raspberry Pi costs about the same as an Arduino board, in the future will there be any reason to put up with the constraints of an architecture like Atmel’s AVR, where we have little RAM, no floating point, and 8-bit registers? The answer matters to those of us who enjoy programming small-RAM MCUs and who have spent years fine-tuning our skills to do so. It also matters to those of us who hope to keep our skills relevant through the middle of the 21st century. Can we keep writing C code, or do we need to start learning Java, Python, and Haskell? Can we keep writing stand-alone “while (true)” loops, or will every little MCU support a pile of virtual machines, each with its own OS?

Long & Short Term

In the short term, it is clear that inertia will keep the small-RAM parts around, though increasingly they will be of the more compiler-friendly varieties, such as AVR and MSP430, as opposed to earlier instruction sets like Z80, HC11, and their descendants. But will small-RAM microcontrollers exist in the longer term (e.g., 25 or 50 years)? I’ll attempt to tackle this question by separately discussing the two things that make small-RAM parts attractive today: their low cost and their simplicity.

If we assume a cost model where packaging and soldering costs are fixed but the marginal cost of a transistor (not only in terms of fabrication, but also in terms of power consumption) continues to drop, then small-RAM parts will eventually disappear. In this case, several decades from now even the lowliest eight-pin package, costing a few pennies, will contain a massive amount of RAM and will be capable of running a code base containing billions of lines…

Circuit Cellar’s Circuit Cellar 25th Anniversary Issue will be available in early 2013. Stay tuned for more updates on the issue’s content.

Electrical Engineer Crossword (Issue 269)

The answers to Circuit Cellar’s December electronics engineering crossword puzzle are now available.


1.     MOSFET—According to Ed Nisley in his Circuit Cellar 265  2012 article, this type of tester characterizes a transistor’s behavior by computing the drain resistance at each combination of measured voltage and current

5.     LORENTZ—Type of force on a charged particle caused by electromagnetic fields

9.     TWEED—Tests your engineering know-how in every issue of Circuit Cellar

10.   HOMECONTROL—In last month’s “Task Manager,” Circuit Cellar Editor-in-Chief C. J. Abate mentioned that this was one of the hottest topics in the magazine’s earliest issues [two words]

12.   TASK—In his article in this issue, Bob Japenga defines this as an instance of a software program that is utilizing CPU resources to accomplish some purpose

14.   WIRTH—Swiss computer scientist who designed the Pascal programming language

16.   ILLUMINATION—An LED’s purpose

18.   CALLBACK—Enables a lower-level software layer to request a higher-level-defined subroutine

19.   ELECTRICALRESISTANCE—German physicist Georg Ohm 1789 – 6 July 1854 first introduced this concept [two words]


2.     SHANNON—Cryptographer known as the “father of information theory”

3.     AUTONOMOUSROBOT—Does not rely on human interaction [two words]

4.     BODEPLOT—Represents a system’s gain and phase as a frequency function  [two words]

6.     EAGLE—Commonly used for PCB design

7.     TACHOMETER—A device that can help you determine revolutions per minute

8.     PROGRAMMABLELOGIC—These types of projects utilize FPGAs, PLDs, and other chips [two words]

11.   THERMOELECTRIC—Type of cooling that relies on the Peltier effect to alter heat between two types of materials

13.   MAGNETOMETER—Used to measure magnetic fields’ strength and intensity

15.   GREENENERGY—Focus of Renesas’s 2012 design challenge [two words]

17.   NONCE—Available for a limited time


Electronic Engineering Crossword (Issue 268)

The answers to Circuit Cellar’s November electronics engineering crossword puzzle are now available.


2.     FLOWCODE—Columnist Jeff Bachiochi taught readers how to use this graphical programming language in his recent article about flowcharting (Circuit Cellar 266, 2012)

7.     LAPLACE—This type of transform is similar to Fourier, but expresses functions into moments as opposed of vibration

11.   RACEWAY—Channel to hold wires, cables, etc.

12.   SENSORSCircuit Cellar’s 250th issue (2011) focused on Measurement and this other topic

13.   LANDS—A metallic contact area

14.   BITTI—Interviewee (Circuit Cellar 253, 2011) who designed the “Witness Camera,” a self-recording surveillance camera

17.   DARLINGTON—This type of pair can be produced using individual transistors or purchased as a single device, as in a 2N6301

18.   WAFER—A slice of semiconductor material upon which monolithic ICs are produced

19.   DIELECTRICCORE—The insulating material that makes up the center of the cable through which the conductors are run [two words]

20.   THERMOPLASTIC—A synthetic, flexible mixture of rosins used as an insulting material


1.     ROUNDKEYS—In his article “Hardware-Accelerated Encryption” (Circuit Cellar 266, 2012) Patrick Schaumont said AES encryption’s real secrecy comes from the periodic additions of these

3.     OILCAN—A type of planar tube, similar to the lighthouse tube, which has cooling fins

4.     VECTORGRAPHICS—In the 1970s, Circuit Cellar founder Steve Ciarcia wrote his first article for BYTE about this topic

5.     VOLTAGECONTROLLED—An oscillator controlled by voltage input; there are usually two types: harmonic and relaxation [two words]

6.     TEMPEST—Describes compromising emanations

8.     ACQUISITIONTIME—In a communications system, the time interval required to attain synchronism [two words]

9.     INTEL—Company credited with making the first single-chip microprocessor

10.   HANDSHAKING—How one device communicates with one or more other devices, at a predetermined speed

15.   VARACTOR—Used as a capacitor to control voltage

16.   SALLENKEY—Active filer, two-pole [two words]