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From: pkopp@houligan.UUCP (Paul Kopp)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Question for 800XL experts
Message-ID: <527@houligan.UUCP>
Date: Sun, 2-Aug-87 09:56:34 EDT
Article-I.D.: houligan.527
Posted: Sun Aug  2 09:56:34 1987
Date-Received: Sun, 2-Aug-87 22:03:06 EDT
References: <7477@shemp.UCLA.EDU>
Distribution: na
Organization: Gould CSD, Fort Lauderdale, FL
Lines: 47

in article <7477@shemp.UCLA.EDU>, khayo@MATH.UCLA.EDU says:
> 
> 
> (stuff deleted)
> Now my main question:
> what is the format in which the 800XL likes data to be stored on
> tape? If it is the TI/99A-like FSK modulation, I could probably
> write a trivial program that would force my Mac to simulate an
> Atari output via a sound synthesiser & the speaker jack - I'd
> then record this & send a cassette to my buddy.

WOW...this sounds like _ALLOT_ of work.  Before I started writing programs,
I would try to convince my friend to buy a $35-$40 XM-301 modem for his
Atari.  You could then download binarys/text to your Mac and transfer them
over to him.

Anyway, to answer your question:
(this stuff comes from _De_Re_Atari_)

Ataris write fixed-length blocks at 600 baud (to tape).

Two frequencies are used:
5327 hz. for a mark (or 1) and
3995 hz. for a space (or 0).

A byte is defined by:

1 start bit (space)
0-7 data bits (marks and spaces)
1 stop bit (mark)

Records should be written to the tape in the form of:

01010101      1st marker
01010101      2nd marker  (markers are for speed measurement)
control byte
128 data bytes
checksum

The control byte is defined as:

$FC  indicates the record is a full 128 byte data record.
$FA  indicates the record is a partial record (less than 128 bytes).
$FE  indicates the record is an EOF.


NEED I SAY MORE?