by Steve Switzer
Q. I have purchased three of the latest Thorn EMI cartridges: Soccer, Jumbo Jet, and Submarine Commander. I also have Star Raiders, Firebird, and Missile Command on cartridge. The Thorn EMI carts have good sound and a good picture, but the picture has "noise bars" at the top and bottom of the screen when played on my ATARI. The other carts on my ATARI play perfectly (no "noise bars"). The Thorn carts play perfectly on my friend's ATARI, so I can't figure out what's wrong. I've tried to "fine tune" my computer through the little hole in the base of the deck, but this has only made matters worse. Any suggestions? --Cris Baylis, England
A. The "noise bars" are probably caused by radio frequency (RF) interference from some source. This might be from the Thorn cartridges, or from your computer, or a combination of the two. It is very possible that the Thorn carts are EPROMs rather than ROMs. Many companies first bring their products out on EPROMs because they can produce these as soon as the programmer is finished, while it still takes some time to mask out a ROM for a cartridge. If the EPROM is improperly shielded, you could be getting RF from the cartridge itself. It could also be caused by the decoupling circuitry in the cartridge. One reason your carts might work on your friend 's machine, but not your own, is that the RF shielding on your machine may not seal properly, and this could allow RF to bleed into the machine. The peculiar combination of your leaking ATARI and inadequately shielded cartridges could be causing the problem.
Q. I would like to compliment ANTIC on the good job it's doing, but I'd like to see a more technical column. It seems to be impossible to get a schematic of the output ports of the ATARI. Thanks to you we have a small idea of how they work, but not how they connect on the inside. Many of us would like to add our own modems or speech synthesizers, but we need the internal diagrams. Where can we get these?--Ray Ives, CA
A. Your timing is good, because this column is going to be in ANTIC regularly to help you solve problems you may be having with your computers and related products. About the schematics, they should be available at your computer shop under the title of Technical User Notes, Atari part #C016555. If your store doesn't have them, drop us a line at Electronic Fantasy, 52 S. Linden Ave. - #I, South San Francisco, CA 94080. We can get them for you.
Q. I purchased my ATARI 800 about six months ago. I thought it was a good value, and I only needed a cassette drive for storage at that time. Lately I have been considering a disk drive. The question is, which one to buy? I see that the Atari 810 can be bought for about $400, and that the Percom double-density master drive costs about $600. Is the Percom worth the extra money? Is the Atari 810 reliable?--Glen Harrod, NY
A. I hope I can be objective about this. In my opinion, both the drives are very good. Reliability problems with the Atari 810 have decreased steadily in the last year or so, and I now consider it very reliable. If you only want one disk drive, I recommend the 810. If anything does go wrong with it, you should be able to get it fixed right in your own back yard. The Percom must be sent away to the factory. But if you are going to get two or more drives, then the price of the Percom master and one Percom slave is about the same as two 810s. This combination has the advantage of double-density mode. There are several new drives on the horizon. It might be wise to check them out before making a decision.
Q. In response to Bruce Fuerbringer's letter on problems with the Basketball and Star Raiders cartridges, I happened to notice a letter in another magazine from a person whose serviceman said that screen inversion was due to undocumented hardware bugs. He further stated that having a full 48K memory might invert the display, or maybe faulty ICs in the cartridge ROM are the culprits. I have never had this problem, but the situation sure sounds confusing.--Mike Sinatra, PA
A. This problem is very common, but it is not caused by the cartridge, and has nothing to do with full memory or undocumented hardware bugs. About two years ago Atari sold a number of 800s with faulty ANTIC chips. The most common symptom was an inverted playfield with the Star Raiders game. The proper correction is replacement of the ANTIC chip.
Q. I recently bought an Atari 5200 video game machine, and I've had to take the controllers in for repair twice already. Now the warranty has expired, and I'm afraid I'll have to spend $20 every month or so to keep the controllers working. What should I do?
A. The 5200 is a very good machine and has developed very few problems.
The controllers, on the other hand, are not so sound. Atari is aware of
this, and has sent newly designed innards to the service centers to replace
the old parts. The company has also extended the warranty on the controllers
(not the 5200 itself) to June 30, 1983. So don't "open" your controllers,
even if you think your warranty has expired, until after that date. Take
them to a service center for repair. Personally, I strongly advise you to
stay out of the controllers completely, because they are very tricky inside.