5 Dec
2014
5 Dec
'14
3:21 p.m.
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.
Rich
Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/