Path: utzoo!attcan!uunet!portal!cup.portal.com!BobR
From: BobR@cup.portal.com (Bob BobR Retelle)
Newsgroups: comp.sys.atari.8bit
Subject: Re: Need a cassette tape drive.
Message-ID: <10329@cup.portal.com>
Date: 22 Oct 88 03:58:32 GMT
References: <736@wsccs.UUCP> <4408@bsu-cs.UUCP> <2170@udccvax1.acs.udel.EDU
Organization: The Portal System (TM)
Lines: 30

Oops... sorry about that...  "macro fingers" hit "done" rather than "edit"..!

Just to add to the discussion of how the cassette drive (C:) works on the
8-bit Atari...
 
As Chris Chiesa indicated, the cassette device is a "special case", and
does not operate as a normal SIO device.  The POKEY chip translates the
logic data into "two tone" audio (much like a modem does), then sends it
to the cassette, which records it as regular audio.  Reading data is the
reverse process, with the audio "two tone" signal being translated back into
logic data.  Addressing the C: device with a LOAD "C:"  or  SAVE "C:"
is what puts this method into action.

A normal audio cassette recorder  *will*  work, but not very well.  The
problem is that most audio recorders have too *good* a frequency response,
and are designed to work with sine waves...  the Atari data recorder has
circuitry to clip the audio, square it off, and restrict the frequency
response to the narrow range of tones coming from the computer.  Thus,
using a Walkman *may* work, but not as well as a 410/1010... I used to
sell Atari software and experimented for a time with multiple recorder
set-ups  to do mass duplication, and the results were never very satisfactory
with audio recorders...  (but what the heck... give it a try..!)
 
In answer to the original request for information about obtaining an Atari
cassette recorder, there is a company called B&C ComputerVisions which
advertises in the Atari magazines,  I see their ad in the November '88
ANTIC magazine.  They used to list the cassette drive very cheaply, and
may still have them.  Other ads in the magazines may be worth calling too...
 
BobR