On Wednesday, 10/12/2005 at 09:48 EST, Adam Thornton
<[EMAIL PROTECTED]> wrote:
> Two objections here:
>
> 1) Those drivers are not easy to find.  They're buried in a
> supplementary rpm to a fairly obscure redbook, and you have to pick
> apart the rpm by hand in order to rebuild the ur stuff.

Who said anything about leaving them in a redbook?  They need to be
dragged out into the light of day, given a good bath, combed and shaved,
and, if necessary, flea dipped.

Or, forget them and start anew.  Or those who have written other
implementations could bring them forward.  Barnard Software's NJE/IP
bridge obviously has reader/punch/printer drivers in it.

> 2) They're pretty slow; I imagine the DIAG interface would be a good
> deal faster.  In most normal cases, this is unlikely to be a
> problem.  In the case *we* tried to use it in, which was mail spam/
> virus scanning and delivery, the ur device was actually one of the
> bottlenecks (not, granted, as bad as the content scanning, but still
> significant).

As I mention elsewhere, never read or write a single record from/to the
spool if you can help it.  Blocked I/O or Diag 0x14 to read.  For bulk
writes, use blocked I/O.

> Oh, third objection:
>
> 3) I had to poll the machine's spool to see if anything had appeared,
> because AFAIK, the ur device didn't offer interrupts to say "Hey!
> Got something new here!"  This may have been my own lack of knowledge
> about how to drive them, though.

A reader throws an unsolicited not-read-to-ready DEVICE END when a spool
file arrives.  (It is equivalent to pushing the START button on a real
card reader.)  This is how WAKEUP works.  The details are in your
always-handy 2821 Control Unit Description manual!  :-)

Alan Altmark
z/VM Development
IBM Endicott

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