Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!gatech!hubcap!ncrcae!ncr-sd!hp-sdd!hplabs!ucbvax!ULKYVX.BITNET!RAMCTE01
From: RAMCTE01@ULKYVX.BITNET
Newsgroups: comp.sys.atari.st
Subject: Writes to ST Cartridge Ports?
Message-ID: <8706292047.AA13208@ucbvax.Berkeley.EDU>
Date: Mon, 29-Jun-87 16:08:00 EDT
Article-I.D.: ucbvax.8706292047.AA13208
Posted: Mon Jun 29 16:08:00 1987
Date-Received: Wed, 1-Jul-87 02:31:34 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: University of Louisville
Lines: 36

I am posting this for a friend who wants to tie into the cartridge slot
of a 512 ST. He is attempting to interface to a video digitizer (from
BYTE magazine - one of Steve Ciarcia's projects). Does anyone have
information on what needs to be done in hardware and software to
accomplish this?

Notes:

    o   Yes, I know the device in BYTE used a serial interface. He
        has to do his I/O faster than that.

    o   I have seen articles/postings which talked about synthetic
        writes to the cartridge port using reads to special addresses;
        this approach isn't fast enough for what he wants to do.

    o   He plans on bringing the Read/Write line out from the processor
        or wherever to the cartridge port.

This seems straightforward, but we've been told that a write to cartridge
memory space causes a bus error - hardly a desirable side effect. Is this
true, and can it be disabled in software?

Although there are perhaps more elegant ways of tying into the ST (DMA
port, etc.), he is pressed for time and needs a quick solution.

Please respond directly and I will post a summary, if anyone wants me to.


Thanks in advance,
Rick McTeague
Electrical Engineering Department
Speed Scientific School
University of Louisville
Louisville, KY  40292

BITNET address:  RAMCTE01@ULKYVX.BITNET