In message <199604111214.IAA03454@Collatz.McRCIM.McGill.EDU> you write: 
> Yes.  dd is not the right tool here.  The effect you want can be
> expressed as "dd ibs=1 obs=10240 ....", but that is ruinously
> inefficient.

Inefficient, but not too slow :)

> With most systems, you can use dd obs=, without specifying an ibs (or
> equivalently specify ibs=512, which is the default), and it will "just
> work"

Unless you need output padded to a larger blocksize :(

> Unfortunately, I know of no other tool shipped with NetBSD that is
> capable of blocking out writes like this.  I have one, called
> "catblock", ...

Is there anything you haven't written?  :)

Thanks...

Also pointed out to me; the 4.4 manuals refer to a "osync" option to dd,
which has no current GNU equivalent.
I fixed my problem by writing to a temp file, so that the read() would
grab however much I asked for, although There's More Than One Way To
Do It (sm).  Thanks for all the help, folks; I got no answers from
my post to UselessNet.