30 Nov
2015
30 Nov
'15
8:20 p.m.
Jerry Weiss
jsw at ieee.org
On Nov 30, 2015, at 7:12 PM, Johnny Billquist <bqt
at update.uu.se> wrote:
On 2015-12-01 02:06, Jerry Weiss wrote:
See page 1-4 "Two tracks, each containing 1024 individually numbered,
firmware-interleaved "records." Firmware manipulates 4 records at each operation
to form 512-byte blocks"
Also figure 1-5. Not only interwoven, but reversed for bi-directional r/w I
believe.
Jerry
The TU58 was a block addressable using a cassette tape drive famously(?) called DECtape
II. File placement on the two different linear tracks was a necessary art, especially
if you were booting RT11 regularly. This helped it to stream or not rewind in sensitive
places. The 1:2 interleave was ?built-in? to the block formatting (see
EK-0TU58-UG-001_TU58_DECtape_II_Users_Guide_Oct78.pdf).
I wasn't aware that it did any block interleaving. But yes, file placement was
extremely important. Are you sure it interleaved blocks?