Weekly Classic Computer Trivia Question (20141205)
RichA at LivingComputerMuseum.org
Fri Dec 5 17:21:47 CST 2014
From: Jerome H. Fine
Sent: Friday, December 05, 2014 3:05 PM
>> tony duell wrote:
>>> Approximately how many DECtapes will fit on a single one terabyte drive?
>> All that were ever made?
> If I remember correctly, a TU-58 tape holds 512 blocks of 512 bytes
> or 262,144 bytes in total or 2 ** 18 bytes
Jerome, "DECtape" without a following "II" refers to *real* DECtape, the
3/4" medium used on DEC's 555, TU-55 and TU-56 DECtape drives. These were
formatted with 578 blocks of 256 18-bit words (even for the PDP-11, which
ignored bits 0 and 1) or 1102 blocks of 129 12-bit words (= 86 18-bit words)
depending on which architecture the drives were connected to.
These were 4" reels, not cassettes.
Vintage Computing Sr. Systems Engineer
Living Computer Museum
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Seattle, WA 98134
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