Newsgroups: comp.lang.postscript
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: LocalTalk and printers
Message-ID: <1990Jul4.164227.6367@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <2414@acorn.co.uk> <1990Jun23.184530.1326@cbnewsl.att.com> <184@heaven.woodside.ca.us> <1363@chinacat.Unicom.COM> <1990Jun27.201333.10418@utzoo.uucp> <3439@adobe.UUCP> <268C0233.50F0@intercon.com> <1990Jul3.173300.6547@zoo.toronto.edu> <3803@rodan.acs.syr.edu>
Date: Wed, 4 Jul 90 16:42:27 GMT

In article <3803@rodan.acs.syr.edu> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes:
>>The biggest problem with it is that it's not available over the RS232 port.
>>People would have written software to speak the printer protocol, whatever
>>it was, but having to add funny new hardware just to talk to the printer...
>
>First, supporting apple/local/talk requires fairly highly timed detailed
>protocools.  If it is supported by the/a main processor, the overhead is
>signifigant...

It would be less significant at lower speeds, e.g. those of RS232.  And
talking to a printer is never free.  Supporting a significant protocol
is the price you pay for error-free flow-controlled transmission with
full 8-bit transparency and "side channels" you can use to inquire about
printer status etc.  It's worth it.

>If  it is to be downloaded to a xxx/talk onlpy processor,
>that adds signifigant complexity to a otherwise almost trivial hardware
>serial (basically) interface...

Having any new hardware interface *at all* is the problem.  And downloading
protocols into auxiliary processors seldom pays off, because then there
has to be some sort of protocol between the host and the auxiliary.

>... Lastly, as a printer/sharing/LAN it has
>severe/major/... limitations.  For a few users or a small network, it
>is great...  For a larger network...

Who said anything about sharing?  I just want one (1) machine to talk
to one (1) printer.  Intermachine communication is better done by an
industrial-strength solution like Ethernet.
-- 
"Either NFS must be scrapped or NFS    | Henry Spencer at U of Toronto Zoology
must be changed."  -John K. Ousterhout |  henry@zoo.toronto.edu   utzoo!henry