DECtape reliability?

Paul Koning paulkoning at
Thu Nov 12 14:26:23 CST 2015

> On Nov 12, 2015, at 1:56 PM, Eric Smith <spacewar at> wrote:
> ...
> Also DECtape does not have a specific directory format. It depends on
> what computer line you are using (12-bit, 16-bit, 18-bit, or 36-bit),
> and in some cases on which operating system you are running.  Some
> systems have software to access foreign DECtape logical formats; I
> think the widest range of DECtape interchange software provided by DEC
> was on TOPS-10.

Either that, or RT-11.  Its FILEX program supports a bunch of different formats including TOPS-10 format.  (It used an odd way to read 36 bit data on a PDP-11 -- not using the read all command, but using the read data command and grabbing the upper 2 bits from a CSR as the words passed by.  Tricky, you have to keep up with the DMA engine.)


More information about the cctech mailing list