DECtape ancestry (Kyle Owen)

Michael Thompson michael.99.thompson at
Sun Mar 21 13:06:43 CDT 2021

> Date: Sat, 20 Mar 2021 16:21:44 -0400
> From: Kyle Owen <kylevowen at>
> Subject: Re: DECtape ancestry
> What systems took advantage of the bidirectional nature?
> Kyle

ADSS on the PDP-9 does an interleave of 6 when reading/writing to the
DECtape. If it runs off the end it reverses direction and keeps going. I
have seen some library files take three passes of the DECtape to fully

Michael Thompson

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