Fleysher.wbst@XEROX.COM.UUCP (02/06/87)
David
<ulysses!gamma!zeta!mb2c!fmsrl7!cideq3!krastes@ucbvax.Berkeley.EDU>
- sorry, I can't reach you from here ("name too long").
There are probably thousands of us out here with 410 recorders gathering
dust. If anyone provides suggestions for using them, please pass them
along.
Dan
-----------------------------------ekijak@ARDEC.ARPA.UUCP (02/10/87)
The 410 records whatever you feed it just like a regular cassette recorder. But when you try to play it back it passes the output from the tape head (after amplification, of course) through two filters. The output of one filter is a dc voltage if a certain frequency is present, and zero or a lower dc voltage otherwise; and the output of the other filter is a dc voltage if a different frequency is present. I don't recall the actual frequencies, but they were something like 4 khz and 6 hkz, corresponding to the square wave frequencies put out by the serial port when doing a csave or list "c:". The two outputs were combined in a comparator (If I remember correctly) and the final output was a high or low TTL signal. This is what got sent back into the serial port when you loaded the saved program back in. If you grab the signal before it goes into the filters, you may be able to recover the original audio. Also, one of the tracks IS an audio track in that on playback, it gets sent directly to the monitor (TV) speaker. I don't know what (if anything) it does on recording (csave'ing).