10b-Computer Memory (Delay Line & DRAM)

After my Nov 3rd lecture in class on early digital computers (ENIAC, EDVAC and UNIVAC) and the role of Presper Eckert, John Mauchly and John von Neumann in their development, we will look at a short video on mercury delay line memory and von Neumann’s First Draft of a Report on the EDVAC. 

You should then post an entry explaining how Delay Line memory and Dynamic Random Access Memory work and how they differ.  Some of the first computers, like the EDVAC and the UNIVAC, used the former.  What are some of the uses for DRAM today?  Once you have visited Micron add an account of the manufacturing process you saw on the tour.

Memory – Eric B

Delay line memory was used in the earliest digital computers. It was a type of refreshable memory that was serial access (sequential). Delay line memory works by having tubes of mercury that store and sending in pulses then having the other part of the memory decode the pulses. Dynamic Random Access Memory (DRAM) is used in most modern memory devices. It works by storing each bit of data in a separate capacitor in an integrated circuit. Like the delay line memory, it is a refreshable memory, but this is also a preventative measure because if power is not refreshed in a capacitor, they will leak charge and lose data. Neither memory can store data once power has been turned off.

Memory~ Desire’ Bounds

            Dynamic ram is the template for all modern memory types. It fulfills the need for a fast, short-term memory solution.  This memory needs to be constantly refreshed with an electric charge to keep its information stored. When the computer is turn off all data is lost.

DRAM is used for lots of things as I learned at micron, IPODS, CD players, automotives, cameras etc.  DRAM is probably used for all modern day memory types. It has a memory space that gives your processor very fast access so it can be written down without slowing down the system. The memory is stored in different places so the data will not be lost. 

From Wikipedia, it says that this memory is refreshable. And it’s also a serial access memory which takes things in a sequential order. Another thing that is different from them is their size. One is bigger than the other. We saw how much bigger the other one was on the tour.

What we say at Micron was the little robots or whatever running overhead picking up wafers and taking them to testing stations.

Memory – Heera Jay

Dynamic Random Access Memory (DRAM) is where a transistor and a capacitor, kind of like a battery, that are paired together to create a memory cell which reperesents a single bit of data. A bit is a binary digit taking a value of 0 or 1. The capacitor holds the bit information (a 0 or a 1) and the transistor acts as a switch that lets the control circuitry to read or change the state of the capacitor. Imagine the capacitor as like a leaky bucket. So inorder to store a 1 in the memory cell, the bucket has to full. But remember that the bucket aka the capacitor is a leaky bucket so as soon as you fill it with 1, it empties out to 0. So in order for the DRAM to work, the CPU has to comealong and recharge all the 1 before it discharges.

Delay line memory works like a ripples in a pond. The delay line memory, the information is introduced to the memory in the form of electric pulses, like the ripples in a pond. These electric pulses go through a medium that transforms the pulses into mechanical waves while going through the medium. But after it comes out of the medium it goes back to being an electric pulses.

Memory – Stephen I

Dynamic random access memory is a type of memory that stores a bit of the given data in different capacitors.  The capacitors would be given an electrical charge in order for the data to not be lost due to leaking in the capacitors.  Delay line memory is a type of memory that uses the vacuum tubes to slow down the data while it is being transfered and copied to another place for use in the future.

Today RAM is used in mostly every product that we use today.  We learned at the Micron tour what their memory chips are used in and I was surprised to learn how we daily use them.

Memory – Laurence B.

Delay line memory consisted of an electrical impulse being propagated through some liquid. Mercury was used because it is could hold many waves of information. The computer that was retrieving the information used an internal clock that would compare the time the pulses were sent with the current time. By knowing what time the information was propagated, it could be looked up and retrieved. Upon finding the propagated wave of information desired, the computer would re-transduce the wave back into an electrical pulse, and the computer would read it. DRAM works by storing each bit of memory into its own capacitor, thus eliminating the need for a mercury filled tubes. When the information is needed, the capacitor would be looked up, and the information would be there for retrieval. The design of the two are totally different, but the ideas are the same, store memory in a way that can be easily retrieved. DRAM is used in computers and other smart electronics today. The cool part about DRAM is that when the power is removed, the memory clears, thus leaving you with a clean place to store small pieces of data for easy retrieval. The manufacturing process of modern day electrical memory is quite different from that of the Delay line memory. The manufacturing of todays memory is all very systematic and clean. The lighting is a dark yellow color so as not to damage the intricate wafer pattern with other frequencies of light. Most of the production is done in the dark by machines, and the actual process is kept very secret.

Memory – Ivan B.

There are a couple key differences between the delay line memory and the dynamic random access memory. The first key difference is how the devices worked. Delay line memory works on the concept of taking an electrical singal and then transducing it into a medium, like mercury or a wire. A mechanical wave would travel through the medium and when it reached the end of the medium, it would transduce back into an electrical singal. There could be many signals that travel through the medium at the same time, but to retrieve any of them one would have to wait until the singals reached until the end of the medium. The dynamic random access memory worked on a different, much simpler concept. The electrical signal would be stored as a bit, in a separate capacitor within an integraded circuit.

The second difference, as already mentioned, is what the devices are made of. Delay line memory had a medium through which it passed which consisted of mercury, magnetostrictive material, or piezoelectric material. Dynamic random access memory consisted of simply a large number of capasitors in an integrated circuit. DRAM memory takes up a lot less space, and it also be used at higher speeds than DLM. DRAM is the type of memory that is most widely used today in devices that require storing data for a short period of time without having to save it for a long time. In the world of today DRAM is used many places which include computers and video game systems.

Memory Chris Cook

Dynamic Random Access Memory (DRAM) runs off of a grid of transistors and capacitors that are used to store bit information.  When an element of DRAM is to be accessed selectors find the appropriate row and column to connect to.  The ability to switch from one element of the array to a completely unrelated element of choice leads this to the random access portion of it’s name.  A significant disadvantage of the system is the requirement of precise voltage control and limitations of access to the elements during refresh periods (In DRAM capacitors lose charge over time).  This is nowhere near the limitations of delay line memory (DLM, not official abbreviation).  DLM takes electrical impulses and converts them to some mechanical function, usually waves, that pass through an object over time and are converted back to electrical impulses at the end.  If it is necessary to store the signals longer they are simply rerouted back into the medium.  Because the signals are in a specific order as a mechanical wave they may only be read as a sequence of data that must finish traveling through the medium before any process can be used to split it apart.  This may be significantly slower than DRAM, however, it was the only method available for a long time.  Another disadvantage is that depending on the chosen medium DLM had to be secured by precise environmental controls and featured additional calculations to maintain as well as read.  Today DRAM is used in various electrical devices that store information for a temporary period of time, but only while powered.  A perfect example of this is the computer you are most likely reading this posting from.  Manufacturing of DRAM is a very long and complicated process I will not be covering today.  Bye bye.

Memory-Nicole O.

          According to wikipedia, the delay line memory is considered to be “refreshable.” This means that it consistently process information from different aspects of the computer and is able to rewrite the process information in the same area with adjustments being made. Delay line is also serial access meaning it is capable of data memory array is accessed in a sequential order that is predetermine. The alternative method was a random access. The random access memory contrasts from delay line memory. The random line access stores data and once accessed it returned the information in any order, not necessarily the order one puts it in. I consider random access a less organized system. Some devices and products that uses DRAM are  digital audio players, digital cameras, PCs, and mobile phones.

Memory – Jhonny E.

From what I can tell both delay line memory and dynamic random access memory both work in a similar matter, such that they both are refreshable memory. Refreshable memory is a process of periodic checking of new information from the memory and rewriting the  information without no modification. But the main difference between delay line memory and dynamic random access memory, and the reason why dynamic would be superior is that dynamic works with random access, and delay line works in a sequential access. Random access is the ability to access information in equal time apposed to sequential access where information would be accessed in order much like a tape. Where if you would want to listen to a song in a tape, you would have to pass many songs, and in a cd you can just skip songs like random access. Today DRAM is most commonly used in most computers and only having to compete with flash memory. During the tour we saw DRAM plates being stored in a clear box, where the box would go through various stations before it would be completed.