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Message: <blockquote data-quote="LINDA_ADERSON_22" data-source="post: 22624549" data-attributes="member: 322784"><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d3/BRL61-IBM_305_RAMAC.jpeg/220px-BRL61-IBM_305_RAMAC.jpeg" alt="" class="fr-fic fr-dii fr-draggable " style="" />Its design was motivated by the need for real time accounting in business.<a href="https://en.wikipedia.org/wiki/History_of_IBM_magnetic_disk_drives#cite_note-15" target="_blank">[14]</a> The 350 stores 5 million 6-bit characters (3.75 MB).<a href="https://en.wikipedia.org/wiki/History_of_IBM_magnetic_disk_drives#cite_note-16" target="_blank">[15]</a> It has fifty 24-<a href="https://en.wikipedia.org/wiki/Inch" target="_blank">inch</a> (610 <a href="https://en.wikipedia.org/wiki/Millimetre" target="_blank">mm</a>) diameter disks with 100 recording surfaces. Each surface has 100 tracks. The disks spin at 1200 <a href="https://en.wikipedia.org/wiki/Revolutions_per_minute" target="_blank">rpm</a>.  Data transfer rate is 8,800 characters per second. An access mechanism  moves a pair of heads up and down to select a disk pair (one down  surface and one up surface) and in and out to select a recording track  of a surface pair. Several improved models were added in the 1950s. The  IBM RAMAC 305 system with 350 disk storage leased for $3,200 per month.  The 350 was officially withdrawn in 1969.</blockquote>

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