Tangle Angles
I'm yet another new Atari owner who's been plagued by CLOAD errors from my 410. So, armed with the April 1983 issue of ANTIC, I decided to do something about it. I added several test points to determine where the failure was occuring. As a result, I found that the data-out line had an excessive amount of jitter when viewed on a dual-trace oscilloscope along with the output of the active filters.
I decided to modify the diode/RC networks between the active filters and the comparator as a possible cure, after checking the DC regulator to the motor drive for ripple. Since performing this modification, I've had no CLOAD errors!
While this modification isn't substantially more difficult than the resistor- replacement mod you recommend, the aligninent does require test equipment that is not found in the average home. However, any competent stereo-service shop should be able to complete the alignment in considerably less than an hour's time.
Stephen Matern
Vice-President
Bonneville Atari Group
(BAG)
Moses Lake, WA
I'm pleased to see that we have so many inventive Atari users out there. I tried your mod, and it works. In essence, you installed a notch filter in the digital-playback circuit to eliminate the overlap between the two tuned filters. This prevents the occasional cross-over you can get with these circuits. My hi-rel mod accomplishes the same thing by tightening the skirts on the response curves. Your solution is a very good one for people who have a proper lab equipment. I suggest that you write a short how to article about your modification that we can publish in this department of ANTIC.
I'm writing for two reasons. First. I'm very curious about the history of the 410 recorder. I have what I call an "old" 41O, which is larger than the "new" 410 and has a tape counter on the lower right of the tape compartment, rather than the upper left. Several of my friends have the new 410's, and this has brought the differences between the two models to my attention. When we exchange programs, my friends often have problems loading programs recorded on my old 410. Furthermore, my old 4l0 can often load programs that were recorded on the new units, even when the "parent" recorder fails to do so. Why the difference between the two models, and why did Atari switch from a reliable recorder to a loser?
I'm also curious about the "hi-rel mod" you've mentioned in several columns.
Rod Smith
Cincinnati, OH
The hi-rel modification is very simple. All you need to do is replace the 10% resistors in the tuned filters with a tighter tolerance pair of resistors. I recommend 1% resistors, but anything smaller than 10% will give you some improvement (by the way, Atari went with 5% resistors in the later-model 410's and 1010's). Since I did my first column on this subject, I've been given a copy of the recorder-troubleshooting manual that Atari sends to its service centers. The resistor I.D. numbers you need are R110 (330K,1/4 watt) and R114 (240K, 1/2 watt). These codes should be printed on the circuit board next to the resistors.
I've never actually seen one of the 1979-vintage 410 recorders (your "old" 410). I first saw a 410 in 1981, and have since seen at least three versions that are called "410 recorders." Check the tolerance of the resistors in your recorder. It's possible that Atari used better components than 10% resistors in the early models. At any rate, try my hi-rel mod on your friends' recorders; I'm sure they will see an immediate improvement.
I read somewhere recently about the problems involved in using cassette recorders to make backup copies of tapes, so I tried it myself. I put a boot cassette on my stereo cassette deck, copied it to my reel-to-reel deck (at 7'/2 ips) and then copied it back to my cassette deck.
So far, my success rate with this procedure is running about 95 percent. The only problem is that when I try to put more than one program on one side of a tape, I'm never able to load the second program. As soon as I get past the frst program, the recorder acts as if there's bad data on the tape and gives me an error message. I've listed to the tape on a cassette recorder and I'm sure that nothing is there. Any ideas?
C.J. Cottle
East Haven, CT
Analog copying of cassattes is, at best, a tricky business. If you have a good audio tape deck and you put just one program on a tape, you will usually get reasonably good results. The trick to putting more than one program on a side is timing. The Atari tape recording process is extremely time dependent. The second file should load properly if you find the right spot on the tape to start the load. This is tricky, even with files written entirely by your computer. Good luck!
Being new to Atari and to ANTIC, I may be beating a dead horse, but do you know of any adapter that permits the use of non-Atari tape units with the Atari 400?
Aaron G. Todd, Jr.
Los Angeles, CA
There are at least three products on the market that claim to let you use a "normal" stereo recorder with your computer. I say "claim to" because I have not actually tested any of these devices. As a result, I cannot recommend any of them personally. I will, however refer you to several ads I noticed in the August 1983 issue of ANTIC. On page 75, the EFD 600 from Essence Peripheral Systems is advertised, and there's an ad on page 99 for the Casadapter from SAR-AN Computer Products. I'm sure that other such devices are also available. If you purchase one of them, please let me know how it works so I can pass the information on to our fellow cassette users.
Is there a way to compare cassette size (tape length) to program size (RAM)? For example, does a 48K program require a C30 cassette?
R.M. Kirby
Chifley, Australia
A program's size is normally defined in terms of how much RAM it requires. To get a feel for the tape length to use for programs that appear in magazines, for example, check the number of K-Bytes of RAM required and use this little formula to determine how much tape you need:
LENGTH= (K-BYTES)*(5 MINUTES) /(8 K-BYTES)
It takes approximately five minutes to load an eight K-byte program, and about 20 minutes to load a 32 K-byte program. I suggest that you time the loading of different programs on your computer and define your own conversion fractor. Don't forget to take the 20-second leader into account.