Learn more. Why does dynamic ram need to be 'refreshed'? Ask Question. Asked 1 year, 6 months ago. Active 1 year, 6 months ago. Viewed times. Calvin Godfrey Calvin Godfrey 2 2 bronze badges. Why is a separate refresh necessary? Remember, a DRAM cell is just one transistor.
It can't do very much. That makes sense, thanks. It should be fairly clear why if you understand what is going on at all in the schematic.
Add a comment. Active Oldest Votes. What does this mean with power and density? The level of charge on the memory cell capacitor determines whether that particular bit is a logical "1" or "0" - the presence of charge in the capacitor indicates a logic "1" and the absence of charge indicates a logical "0".
The basic dynamic RAM memory cell has the format that is shown below. It is very simple and as a result it can be densely packed on a silicon chip and this makes it very cheap. The basic memory cell shown would be one of many thousands or millions of such cells in a complete memory chip. Memories may have capacities of Mbit and more.
To improve the write or read capabilities and speed, the overall dynamic RAM memory may be split into sub-arrays. The presence of multiple sub-arrays shortens the word and bit lines and this reduces the time to access the individual cells. The word lines control the gates of the transfer lines, while the bit bines are connected to the FET channel and are ultimately connected to the sense amplifiers.
One of the critical issues within the dynamic RAM is to ensure that the read and write functions are carried out effectively. As voltages on the charge capacitors are small, noise immunity is a key issue. One of the problems with this arrangement is that the capacitors do not hold their charge indefinitely as there is some leakage across the capacitor.
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Forums Hardware Systems. As described above, according to the method of refreshing the dynamic RAM embodied by the present invention, when accessing any of the real-time high-speed devices such as the floppy disc driver unit, such a refreshing process can be smoothly executed by using relatively simple circuit means without causing the time to run out of the effective life of the needed data, and yet, without destroying the data contained in the dynamic RAM at all.
The present invention thus described in reference to the annexed drawings will obviously be suggestive of any derivation or modification from the spirit and scope described therein by those skilled in the arts. What is claimed is: 1. Means for refreshing a dynamic RAM in a computer system having a central processor, a dynamic RAM accessible by said central processor and having a plurality of memory elements, and at least one input-output port comprising: burst mode refresh means for refreshing all said memory elements of said dynamic RAM, said dynamic RAM not being accessible by said central processor when refreshing is performed by said burst mode refresh means;.
USA en. JPHB2 en. DEC2 en. GBB en. Self-refresh system for use in a field memory device operating without reliance upon external control. Circuit for providing synchronous refresh cycles in self-refreshing interruptable DRAMs. Method for synchronizing refresh cycles in self-refreshing DRAMs having timing circuit shutdown. Circuit for synchronizing refresh cycles in self-refreshing drams having timing circuit shutdown. Semiconductor device in which the number of word lines selected simultaneously in a refresh mode is externally selectable and method of manufacturing the same.
Apparatus and method for in-parallel scan-line graphics rendering using content-searchable memories. Digital computer having a system for sequentially refreshing an expandable dynamic RAM memory circuit. Apparatus and method for determining video encoding motion compensation vectors. Dynamic memory system which includes apparatus for performing refresh operations in parallel with normal memory operations. USB2 en. JPSA en. DEA1 en. GBA en. Multi-port memory device with multiple modes of operation and improved expansion characteristics.
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