Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!UIAMVS.BITNET!AWCTTYPA
From: AWCTTYPA@UIAMVS.BITNET ("David A. Lyons")
Newsgroups: comp.sys.apple
Subject: CDA capabilities, ADB splitter
Message-ID: <8804120050.aa03119@SMOKE.BRL.ARPA>
Date: 12 Apr 88 05:41:16 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 56
X-Unparsable-Date: Monday 11 Apr 88 11:40 PM CT


>Date:         Sat, 9 Apr 88 19:58:00 EDT
>From:         SASQUATCH%ALBION.BITNET@CUNYVM.CUNY.EDU
>Subject:      mixed bag
>Comments: To: info-apple@BRL.ARPA

>What are the practical limitations of CDAs?  I'm thinking along the line of a
>program that's a CDA.  It'd be rather nice to be able to call up my modem
>program from with another program and run it, then return to the other
>program.

You might want to look into a thing called SoftSwitch from Roger Wagner
Publishing.  It's a CDA that lets you switch between 3 separate 128K
environments (between 3 ProDOS 8 or DOS 3.3 programs, but not ProDOS 16).

>Would it be possible to write a modem software that worked as a CDA

Yes.  There are some very simple modem programs available as CDAs--I haven't
seen one that does terminal emulation or up/downloading yet.

>or write a CDA that could call in and run a specific piece of software and
>then return you to the software from whence you came?

Yes, but there are some very non-trivial problems.  It might not be possible to
follow all the rules, so there would be compatibility problems.  (Basically,
a CDA can get called when all the bank 0 memory is already being used, and
it has to break some strange things to use it.)

>About mice.  I don't really care for them.  Is it possible to wire a regular
>joystick up to the appropriate connector and use that instead of a mouse?
>I work with rather restricted desk space and would rather move a joystick than
>have to constantly clear space for that silly mouse.

I think someone already suggested you look into trackballs--I agree.
It would be possible to write a driver for your SYSTEM.SETUP directory that
would keep reading the joystick n times per second and calling FakeMouse to
tell the event manager that the mouse is there.  There would be a few problems
with this, like the difference in resolution--the joystick port returns
(0..255,0..255), but you need 0..639 horizontal positions to be able to
put the "mouse" anywhere you want.

>On a related note, would there be any problem makeing an ADB splitter
>so that I could hook my mouse (or, hopefully joystick :-) to the back of the
>apple, then plug my keyboard into that?

Yes, there's a problem--WHERE DO YOU GET FEMALE ADB CONNECTORS?  Other than
that, it will work just fine.  The 2 connectors on ADB devices are wired
straight-through anyway, so everything is in parallel logically even if it
*looks* like it's serial from the way cables go from one device to the next.

>Kevin Lepard
>Bitnet:  SASQUATCH@ALBION

--David A. Lyons  a.k.a.  DAL Systems
  PO Box 287 | North Liberty, IA 52317
  BITNET: AWCTTYPA@UIAMVS
  CompuServe: 72177,3233
  GEnie mail: D.LYONS2