John writes:
> Well, I seem to remember the IRG as being 0.5 inch.
>
> Assuming the record size to be 16,384 bytes, at a tape density of 6250 bpi,
> a record (16K bytes) takes up approximately 3.1214 inches of tape
> (including the 0.5 inch IRG).

Hence the ;MAXTAPEBUF option on :STORE that, I believe, causes it to
create 32,768 byte records, cutting the IRG overhead in half.  Of course
STORE has to bypass the file system to perform reads and writes this
large, which limits the number of tools that can operate on such a
tape on a 3000.

G.