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 – Wes Vullo

Delay-Line Memory was a primitive memory technology that was used in the earliest digital computers. Information within Delay-Line Memory was nothing but electrical pulses transformed into mechanical waves then passed through a medium, such as mercury. Delay-Line Memory was sequential access, meaning memory was accessed in a sequential order. Dynamic Random Access Memory (DRAM) on the other hand was not sequential, and specific bytes of memory can be accessed whenever and however needed. DRAM uses one capacitor and one transistor per one byte of memory to store the electrical pulses as a charge. Today DRAM is the most common used memory type, and there are many different types of it. DRAM is used in personal, business, and enterprise computers, and even in the console gaming industry. Currently, new DDR3 SDRAM is the newest innovation in DRAM, and is capable of transferring data at eight times the data rate of the memory cells it contains.

I do not remember the full manufacturing process that we saw at Micron, but I do remember him stating that the machinery used within it costed millions. One machine had a price tag of 42,000,000. I also remember our tour guide stating that it costed around 10,000$ an hour to run each individual machines. It is interesting to know what kind of machines and technology is needed to produce DRAM.

Memory – Wesley C

The essential idea behind Delay Line memory is processing an information pattern into a path that contains delay. To keep this stored as memory, the end of the delay path is connected to the beginning, which thus forms a closed loop in which the information pattern follows. “A delay-line memory resembles the human device of repeating a telephone number to one’s self from the time it is found in the directory until it has been dialed.”

Random Access Memory (RAM) consists of an integrated circuit, made of transistors and capacitators. These capacitators are used to hold bits of information, while the transistors allow for changes of this information. Electron-filled capacitators represent a 1, while none represent a 0. However, since capacitators lose their electrons quickly, a memory controller must be present to refill the capacitators with electrons, and thus keeping the information alive.

Both methods of memory are volatile, meaning the information is lost when the power is lost. Delay line memory is accessible sequentially, which means it is relatively inefficient. RAM allows for direct access, which is faster. However, the refreshment of memory storage takes time, and slows down memory.

Source:
http://www.decodesystems.com/delay-line-memory.html
http://www.howstuffworks.com/ram.htm

Memory-June Sri

Delay line memory is a computer memory that was used on some of the earliest digital computer. The information is introduced into memory in a form of electric pulses. Electric pulses are converted into mechanical waves. Mechanical waves then pass through a medium such as mercury. When mechanical waves reach the end of the medium, the waves would be transformed into electric pulses. Electric pulses refresh the memory of the computer. The Delay line memory was a refreshable memory and serial access. The refreshable memory was a process of reading an information from a memory, and overwrote the existing information when the new information was added. “Serial access” means that the order sequence to access the memory is predetermined. The data piece is returned in order.

Dynamic random access memory (DRAM) is a computer data storage that stores each bit (binary digit, a basic unit of information storage) of data in separate capacitor within an integrated circuit. The integrated circuit allows the stored data to be accessed in any order, for DRAM, in random order. The stored sata can be accessed randomly, so that any piece of data can be return regardless of its physical location. The information is represented by charges that are stored on the capacitors. It fades overtime, so it must be repeatedly refreshed in order to reserve the information. In today’s society, DRAM is used in most PCs.

Memory – Ryan C

Delay line memory was the first type of memory used in a digital computer. It works by sending an electric pulse through a medium of some kind by converting it to a mechanical wave. The medium slows the signal down enough to be measured. This time measurement is the value that is stored in the memory. Dynamic random access memory, on the other hand, uses a single capacitor and a single transistor per byte of memory to store the electric signal as a charge, which may be accessed on command. However, since capacitors lose charge over time, the charge must be recharged or ‘refreshed’ every so often, otherwise the memory is lost. One of the main differences between delay line memory and random access memory is that delay line memory must be accessed sequentially, or in a specific order. This can be thought of as accessing a song on a cassette tape. To get to the beginning of a specific song, one must fast forward through all of the songs before it. This method of memory takes a significant amount of time because all of the memory that appears before the desired location must be accessed before the one that is desired is accessed.  Random access memory, however, can access parts of its memory without going through all of its stored memory. This would be like accessing a song on a CD: it is possible to skip to the desired song directly without listening to the other songs on the CD. This enables faster access to memory, which speeds up computing. Also, it is easier and cheaper to use a capacitor to store a charge than to measure the time it takes an electric pulse to travel through a mercury tube. This makes DRAM an obvious option for many modern computing devices.

Memory – Marlon

The Delay Line Memory basically inputs an information pattern through a delay, like mercury or quartz, that becomes a closed loop that is able to repeat the information pattern once the end of the delay path is reconnected to the beginning. A good example of this process is that “a delay-line memory resembles the human device of repeating a telephone number to one’s self from the time it is found in the directory until it has been dialed.” (Delay-Line Memory). Meanwhile, the Dynamic Random Access Memory stores bits and pieces of information in different capacitors in a circuit. The DRAM’s capacitors “leak charge, the information eventually fades unless the capacitor charge is refreshed periodically.” (DRAM). The DRAM contains word lines (rows), and bit lines (columns) that create a web of transistors and capacitors per cell. The transistors helps access the stored information and the capacitor stores the information. The amplifier gives a positive feedback to the cells and refresh the storage cells. These are some differences that Delay Line Memory and Dynamic Random Access Memory have, but they both store information. It is just stored it different ways.

Source:

Delay-Line Memory. <http://www.decodesystems.com/delay-line-memory.html>.

DRAM. <http://en.wikipedia.org/wiki/Dynamic_random_access_memory>.

Memory – Robert S

Delay Line memory and Dynamic Random Access Memory (DRAM) were two different types of memory used in early computers. Delay Line memory used electrical pulses to create mechanical waves and send them through a medium, such as mercury. Once these waves reached the other side of the medium, they were turned back into electrical pulses, amplified, shaped, and sent back into the medium at the beginning. However, DRAM stored each bit of data into it’s own capacitor in an integrated circuit, but this memory constantly leaks charge, so it needs to be refreshed periodically. The main difference between Delay Line memory and DRAM is that Delay Line memory could only be accessed in the order that it was entered, whereas any part DRAM can be accessed. DRAM is still used today in personal computers, game consoles like the Xbox or Playstation, and other devices.

DRAM vs. Delay Line Memory – Joey M

Dynamic random access memory and delay line memory are similar in the sense that they both temporarily store data until it is needed to be accessed, then remove it once it is no longer needed. However, they both go about different ways of doing this. DRAM stores every bit of data in its own separate capacitor which can be accessed by its own transistor. This design is very simple yet efficient. Delay line memory stores data by inducing electric pulses and then transforming them into mechanical waves, which are amplified and sent through a medium such as mercury. The data can then be read by measuring the delay of the mechanical wave going through the medium. The advantage of DRAM is its simple design and reliable technique.

Memory- Rich M.

Delay line memory and Dynamic Random Access Memory (DRAM) are two different types of digital computer memory.

Delay line memory operates as a serial system for storing data in the short term. The delay line memory operates by transmitting and receiving sound transmitted through a medium such as mercury or quartz crystals. by receiving and amplifying these signals it could store the information to be used in later processes. unfortunately, delay line memory is serial and can only store one item at a time when a new line is stored the old one is erased.

DRAM is the type of memory found in modern day computers. DRAM operates on the principle of using binary code to store the information, in the form of electricity, in resistor-capacitor pairs. DRAM is not a serial access system. It is random individual parts can be erased or changed without affecting the other parts.

The other than the operating principles, the size of the two types of memory vary greatly. The delay line memory unit was part of a computer that took up 800 square feet. The DRAM chips are part of modern laptop computers.

Memory – Michael

The basic concept of Delay Line Memory is to insert a pattern of information into a path containing delay. The end of the delay path is connected to the beginning through amplifiers and timing circuits allowing the information to recirculate. This recirculation causes delay which is used as a type of memory. A standard Delay Line consists of a delay medium and two transducers. These transducers convert electrical signals into mechanical stress. The mechanical stress applied to the delay medium travels through a prescribed path as an acoustic wave. This wave in turn applies a mechanical stress on the output transducer reproducing the electric signal. Dynamic Random Access Memory , or DRAM, is one of the most commonly used memory modules in personal computers. DRAM works by storing its information in a cell which contains a capacitor and a transistor. This means that each bit of information is stored in a separate capacitor within an integrated circuit. This is an effective way to store information, but because the capacitors slowly loose charge they must be recharged every few milliseconds. It is because of the recharge this system is called Dynamic memory insted of Static memory. Unfortunately if the computer is turned off or looses power while using this type of memory the information will be lost.