[Info-vax] TK50 - this is annoying...

[glen herrmannsfeldt]

George Cornelius <cornelius at eisner.decus.org> wrote:

(snip, someone wrote)

>> I once met someone who had used DECtapes and he had been very impressed
>> by them in their day, but he was at least 20 years my senior.  IIRC he
>> described some mechanism where they skipped alternate blocks when
>> reading or writing so that the tape speed could be higher, and those
>> skipped blocks were used when the tape was travelling in the opposite
>> direction.

> I had heard that the data was written twice and always assumed (I
> suppose correctly) that the extra blocks were for redundancy.  That
> they might have been written in reverse bit order never occurred to
> me.

The data is written twice, in parallel. Three data bits on 10 tracks.

-- glen