super@CSA1.LBL.GOV (Michael Helm) (02/18/88)
I'm trying to get some information on Asynch Appletalk, which is supposed to enable MACs to connect to an appletalk network via modem or other serial link. (Origin: Dartmouth University ???) Does anyone know anything about this product, namely, availability, utility, features, limitations? Thanks for your attention, Michael Helm M_Helm@lbl.gov (arpa), super@lbl (bitnet), csa::super (HEPnet) UC-LBL
DAVID@DARTCMS1.BITNET (David Avery) (02/18/88)
Michael Helm and others have inquired about the Asynch AppleTalk package
developed at Dartmouth. We've tried to answer the most common questions
about the package in this note, but please feel free to direct specific
questions individually to me and I will prepare a follow-up posting providing
those answers to the list.
What is Async AppleTalk?
Async AppleTalk is a Macintosh driver and desk accessory which allow a user
to access AppleTalk resources (file servers, laser printers, etc.) over a
dial-up RS-232 ("async") link. The driver replaces the standard AppleTalk
driver and causes the LAPWrite and LAPRead routines to send or receive the
packets on an async link, instead of the 230.4 kbps LocalTalk cabling (as
it has been re-named).
Async AppleTalk presumes an eight-bit data path, but honors Xon/Xoff flow
control. An escape mechanism allows it to send arbitrary data.
How can I use Async AppleTalk on my campus/office/home?
You'll need some other gadget to bridge between an Async AppleTalk and a
high speed link. Several commercial companies have announced hardware
which will solve this problem (Solana Electronics in San Diego, CA, Shiva
Corporation, Cambridge, MA). Contact them for price and availability in-
formation.
How do we use Async AppleTalk at Dartmouth?
We have a campus network with RS-232 ports which we have programmed to ac-
cept Async AppleTalk messages from the Mac. The port then sends them out
on a standard (230.4 kbps) wire. This makes file servers and laserwriters
available to Macs which have dialed in over Async AppleTalk. (AppleShare,
LaserWriters, InterMail, and a host of other utilities and public domain
games work just fine...)
Is Async Appletalk compatible with all versions of the system software?
I have tested Async AppleTalk with Finder 4.1/Sys 2.0 and greater. I have
also used Async AppleTalk with a Mac/XL, 512K, 512Ke, Mac Plus, Mac SE and
Mac II.
Apple Computer is also working on new system software which will allow you
to switch between various kinds of links: their LocalTalk Network (230.4
kbps), 10 Mbps Ethernet, and other protocols (such as Async AppleTalk).
The current version of Async AppleTalk (2.1.1) disables this switching ca-
pability. Once you start Async AppleTalk, you cannot use an alternate link
until you reboot or hangup Async AppleTalk. When the new system software
becomes available, we will modify Async AppleTalk to be compatible.
Apple will be releasing a version of Async AppleTalk which uses the control
panel as the user interface. This will allow it to be installed at boot
time, as well as other new features. I have no release date at this time.
Is Async AppleTalk compatible with TOPS, MacServe and AppleShare?
Async AppleTalk works with AppleShare (the server must be on a 230.4 kbps
link). It does not work with TOPS 1.0; I have not tested version 2.0. It
does not work with MacServe (Async AppleTalk unregisters the names which
MacServe registers on startup).
Will it run on a Mac XL?
Async AppleTalk runs fine with a Lisa/Mac XL.
Can I use my XXX hardware with Async AppleTalk?
The answer is: sometimes. For a full answer, you need a bit of background:
There are two useful things to do with a box which has one AppleTalk port
and one async (RS-232) port. Async AppleTalk will do one, but not the
other.
1. Async AppleTalk is designed to accept AppleTalk packets (which are se-
quences of bytes in a predefined format) over a modem or other RS-232
link, and to send them into an AppleTalk network as if the Mac were di-
rectly connected. Thus, Async AppleTalk "replaces" a normal AppleTalk
link with a telephone link.
2. To connect your ASCII terminal or terminal emulator to an AppleTalk
network (for example, to share a modem) you need a device which accepts
single characters from an async device (the terminal), wraps them in an
AppleTalk packet, and sends them across the AppleTalk network. The
technical term for this is a Packet Assembler/ Disassembler (PAD).
Async AppleTalk does *not* do this. Don't worry, there are commercial
companies working on this, too.
You are correct to suspect that the same hardware could do these two things
(using different software). Some of the vendors above provide boxes which
perform both functions. If you already own AppleTalk hardware, contact
your vendor to see if they will offer these capabilities.
Has Async AppleTalk been implemented in a host computer??
Not yet. Dartmouth has no plans to come up with such a package in the near
future. Installing Async AppleTalk on a host only gives one piece of the
total puzzle, though. For Async AppleTalk to be useful on a host, you'll
need to add many of the upper layer protocols (DDP, NBP, ATP, PAP, ASP,
AFP, etc) to provide real service. It is possible to think about grafting
Async AppleTalk into the Columbia AppleTalk Package (CAP) on Unix (CAP is
freely available from Columbia University), but it's a non-trivial imple-
mentation project.
How was Async AppleTalk developed?
Dartmouth obtained a source license for the standard AppleTalk driver, and
replaced the 230.4 kbps LAP routines with code to send the packets over an
async link. The desk accessory was completely developed at Dartmouth.
Both modules are written in MPW assembler.
How is Async AppleTalk being distributed?
Dartmouth is distributing Async AppleTalk free of charge. The package is
derived from copyrighted Apple Computer source code, with copyrighted
changes made at Dartmouth. Consequently, we ask that you observe the fol-
lowing conditions: please retain all the copyright information (both Apple
Computer and Dartmouth College), and please don't charge money for it.
Otherwise, feel free to use it or pass it on to anyone. If you want to use
it in a commercial product, get a copy of our distribution policy: it's
included with a whole lot of other information about Async AppleTalk. Send
a disk (800K) in a mailer, and we'll send all the information.
---------------------------
Rich Brown Phone: 603/646-3648
Manager of Special Projects EMail: richard.e.brown@dartmouth.edu
Dartmouth College AppleLink: A0183
Kiewit Computer Center
Hanover, NH 03755 NOTE: Dartmouth will join Internet in March '88
David Avery Phone: 603/646-2717
System Manager Bitnet: DAVID@DARTCMS1
Dartmouth College CSNet: DAVID@DARTCMS1.DARTMOUTH.EDU
Kiewit Computer Center UUCP: ...IHNP4!DARTVAX!DAVIDA
Hanover, NH 03755P9684@QZCOM.BITNET ("Peter Freund") (02/20/88)
Async AppleTalk works very well with TOPS 2.0. It works with TOPS 1.0 if an INIT-file (supplied with SHIVA NetSerial) is present. TOPS & SHIVA even annonces the dial-in-access-capability in their advertising - all in one. SHIVA: 617 6612026, TOPS: 415 5495900 Peter Freund, Software Plus, SWEDEN