Changeset 219 in t29-www for en/computer/storage-media.shtm
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- Nov 24, 2010, 10:36:53 PM (13 years ago)
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en/computer/storage-media.shtm
r184 r219 111 111 112 112 <p>During the years the capacity of core memory devices was increased more and more while the dimensions were shrinked accordingly. This picture shows a core memory plane made in the time frame 1975 - 1978. The area shown equals 113 that of the 144 bit memory by Triumph shown earlier. Now there are more th en 16000 cores on the same area. The individual cores can only be seen with the aid of a magnifying glass. The whole core memory block contains 16 planes like this containing more then 256000 single cores (this is equivalent to 32 kB of data) occupying a volume of about 2.5 cubic decimeters. This device marks the end of the era of core memory.</p>113 that of the 144 bit memory by Triumph shown earlier. Now there are more than 16000 cores on the same area. The individual cores can only be seen with the aid of a magnifying glass. The whole core memory block contains 16 planes like this containing more than 256000 single cores (this is equivalent to 32 kB of data) occupying a volume of about 2.5 cubic decimeters. This device marks the end of the era of core memory.</p> 114 114 115 115 <p>The smaller the individual cores the faster the access time – this device features an access time of only 200 ns. One drawback of core memory is that reading the information stored in a row of cores destroys the information. So every read access has to be followed by a write access to retain the information (reading from a core memory takes more time than writing to the memory which is a rather unique "feature" of this technology).</p> … … 154 154 <p>While research and development in the Goddard Space Flight Center of the US space 155 155 program, NASA, the american government closed a deal with UNIVAC to develop a 156 storage medium with a total input power less th en 1 Watt, non-destructive readout156 storage medium with a total input power less than 1 Watt, non-destructive readout 157 157 (that is, no more neccessarity to write the informations after reading them), 158 158 high capacity, low cycle time and functionality in a temperature range from 159 159 -20° C to +50°C (-4°F to 122°F). 160 <br/>In this way the plated wire storage was developed, based on a c uple of160 <br/>In this way the plated wire storage was developed, based on a couple of 161 161 genious ideas. Unfortunately, nowadays it is very error-prone.</p> 162 162 <p>Clicking on the photography will yield further informations about the … … 170 170 <img src="/shared/photos/rechnertechnik/speichermedien/lochband-combitron.jpg" alt="A two channel punched tape from the DIEHL combitron calculator" width="424" height="322" /> 171 171 <p class="bildtext"> 172 As already described before (section <a class="go" href="programmable.shtm">programmable 2nd generation desktop calculators</a>), the DIEHL Combitron calculator used a time delay memory (like the magnetostrictive memory described elsewhere). Since this type of memory is volatil y, DIEHL needed a non-volatile memory for the overall control of the machine. This had been implemented using a two channel punched tape. The first channel serves as a clock channel while the second channel contains the actual control data.172 As already described before (section <a class="go" href="programmable.shtm">programmable 2nd generation desktop calculators</a>), the DIEHL Combitron calculator used a time delay memory (like the magnetostrictive memory described elsewhere). Since this type of memory is volatile, DIEHL needed a non-volatile memory for the overall control of the machine. This had been implemented using a two channel punched tape. The first channel serves as a clock channel while the second channel contains the actual control data. 173 173 <br/>During the startup of the calculator, the contents of this punched tape were copied to the time delay memory which then took over control of the machine. 174 174 </p>
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