Electronic Technology Marches Forward to The P-RAM

Watching the change in electronic technology for nearly 7decades now has been an exciting trip. I was 13 years old when I saw a dial phone for the first time. When I say dial I don’t mean a phone with buttons on the front of it; I

Rotary Dial Phone (For many years available in black only)

mean a phone with a disk having 10 holes in edges of it so we put our finger in one of the holes corresponding to the number we wished to dial and turned the disk until our finger hit the stop then we removed our finger so the disk or dial could rotate back to its resting position giving pulses corresponding to the number we dialed. Then we did the same with the next number in the sequence of a telephone number we wanted to call.


Before we had the dial phone our telephone was a wood box with a crank attached to a generator which was used to alert the operator that we wanted to made a call. Even when we got the dial phone it only worked for local calls. For long distance we dialed 0 for the operator and she placed the call for us (not so greatly different from the old crank on the wall).


I well remember the first television sets to come into town. Dwight D. Eisenhower was the first president of the United States to have his inauguration televised. There were three television sets in Meridian, CA where I lived at the time. We kids were divided up into three groups and each group went to one of the three houses to watch the proceedings. That was 1953, I was 10 years old and that was the first time I had seen a television set.


I could go on reminiscing but that is not the purpose of this post. What I really want to discuss is the movement to a new form of memory called the P-RAM or Phase Random Access Memory.


A few years back there was basically two forms of memory chips, the Read Only Memory (ROM) and the Random Access Memory. The major difference was the

RAM board in computer

ROM was manufactured with the desired information permanently etched in the chip.  The RAM had volatile memory which means the stored information was lost every time it was powered off so the difference was clear.


The difference between the two became a little less clear with the advent of the PROM (Programmable Read Only Memory).The PROM could be programmed by the customer but after the PROM was programmed it could not be changed so the programmer had to be sure the information was correct before pushing the execute button on the PROM burner.


Then the creek was muddied up a little more with the EPROM (Erasable Programmable Read Only Memory). If there was a desire to change the


program the EPROM was placed under an ultraviolet light for about an hour and it was ready to be programmed with new information but don’t let it sit under the light too long or the chip would be destroyed.


It had to happen; the EEPROM (Electronic Erasable programmable Read Only Memory) was born. This allowed the program in the ROM to be changed without removing the ROM from the unit in which it was placed.


Meanwhile somewhere along the line Integrated Circuits manufacturers started producing RAM with nonvolatile memory. Now the major difference between RAM and ROM is the way they are used more then the way they are built. The RAM’s have easy access to change the information in them while the ROM’s do not have easy access to the program.


The newest innovation to the logic memory group is the Phase-Change Random Access Memory (P-RAM) also called Phase Change Memory (PCM).


The P-RAM is a form of non-volatile memory which is not based on gates like

Schematic symbol for memristor or memresistor

other RAM systems use but is based on a technique known as memresistor some times written as memristor (short for “memory resistor”).  Memresistor is a much faster memory system then the memory built on gate circuits.


As far as the latest information I could fine the flash memory is still able to be built on a smaller scale then P-RAM which is its greatest disadvantage. It is believed by engineers that future models of P-RAM will be able to be constructed on a much smaller scale the conventional RAM because state of the art RAM relies on gates which can only be reduced in size just so much.


I would not recommend you run down to your favorite electronic parts store and ask for P-RAM’s because they are not yet commercially available but I am sure that in the not too distant future we will see the memory of new ham radios based on P-RAM.


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2 Responses to Electronic Technology Marches Forward to The P-RAM

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