Subject: Re: Re[2]: IP over 1394 isoc useful?

From: Peter Johansson <[email-masked]>
Date: Tue, 15 Jun 1999 19:06:36 EDT

In a message dated 99-06-14 22:17:55 EDT, [email-masked] writes:

<<If the isoch data is synchronized to the speed of the printer, and it takes
more than 2 seconds to print a page  (30 page/minute printer or slower), what
happens if there is a new device connected that wants to be IRM in the middle
of the transmission of this synchronized image?

I am a proponent of having enough buffer allocated so bus perterbations don't
show a usage problem.  However, the synchronization of electronic data to a
mechanical engine is best done in a very captive environment, I think.>>

Jim (and everyone else), I'm not setting out to persuade you that isochronous
printers make sense. I'm just observing that a number of companies are
already concinved that they do and that the buffer savings can run to tens of
megabytes and they are prototyping these products. Just one such example was
shown by Fuji Xerox here at the Nikkei 1394 Seminar in Tokyo yesterday.

Regards,

Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

[email-masked]

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From: Subrata Banerjee <[email-masked]>
Date: Tue, 15 Jun 1999 23:59:23 -0400

Regarding iso. service for printers:

While trying to understand what convinced some printer companies to use
IP over 1394 iso. service...

Can't a printer driver that employ flow control with the printer and send the
data via asynchronous packets save the megabytes of memory just as well?
Printing speed depends on the amount of graphics/text to be printed that
vary from sheet to sheet. Printers also need some breathing room when a
new sheet starts, when paper jams, and when paper runs out. In such situations
async. mechanism would provide better flexibility. Given a typical printer's
speed
and speed of a 1394bus, bandwidth reservation might not be an issue.

Regards,
Subrata