Q. Where did you dig up this clown Switzer, and what's the idea of letting him use ANTIC to drum up business? I refer to his response to a question about cleaning disk drive heads in the ATARI CLINIC department of your May issue. He correctly recommends the use of cleaning sticks, then he tells the guy to use rubbing (isopropyl) alcohol. He should know rubbing alcohol has oils in it." I suggest Mr. Switzer correct this error in his column at the earliest opportunity. I must also disagree with his recommendation against cleaning disks. I would expect that many ATARI users cannot accurately locate the disk-drive head while looking the drive door. I firmly believe that for any non-technical user, a brand-name cleaning disk ... is far less likely to do damage than someone blindly poking around with a cleaning stick. --Gary Crowell, CA

A. Normally, I would not answer a letter with such insulting remarks, but this is an important area that I guess I should cover again. I take this column very seriously and I research the answers using my own people as well as qualified outside personnel. I am not using this column to promote myself or my business, it just so happens that outside of ATARI we are one of the most experienced service centers in the country. As to your information on isopropyl alcohol, to get an outside opinion I called an engineer at Tandon in Sunnyvale, CA. He told me that all he uses is isopropyl alcohol, and that he has never heard of any problems with it. I also asked him about cleaning disks and he said that they don't recommend them to anyone. If you don't believe this man or me, then take the chance of destroying the head on your drive and use a cleaning disk. And at the risk of promoting my business, when you burn out the head on your drive, send it to me and I'll be glad to replace it for you (for a price).

*Actually, Steve stipulated isopropyl, not rubbing alcohol. We editorially inserted "rubbing" in his copy to clarify" his answer, and for this we apologise. Rubbing alcohol is not based on isopropyl, but on ethanol, and does contain oils and other chemicals that might damage heads.--ANTIC ED

Q. I have an older 810 and I am thinking about getting a data separator. Do you think it is worth the money? Also what does it do! -G. Miller, CA

A. The purpose of a data separator is for the drive to differentiate between the clock guise and the data pulse. The 810 has a data separator built into the 2771 controller chip, but this doesn't work as well as it should. When we speak at user group meetings, I always recommend against spending the money on a data separator. The reason is, there has not yet been a drive that we couldn't get working perfectly without one.

Atari came out with the data separator because many drive owners were opening their drives and messing with the speed. The data separator allows you to read disks that are not written at precisely the right speed. By the way, most of the speed-adjustment programs out there don't work, and the ones that do don't update the screen fast enough to tell you if the speed is fluctuating rapidly (very important). Also, the speed of an 810 should be 288 rpm, not 300. Do not use the strobe hole on the bottom of the drive plate to adjust speed, because it is set up for 300 rpm.

Q. I took the memory board out of its plastic case on my ATARI 800. After I did this my computer started to lockup during prolonged programming. What would cause this? --Mr. Jesop, CA

A. Lock-up can be caused by many things. But your question explains exactly where your problems lie. The plastic case does two things: First, it physically stabilizes the board in the slot. When you remove the cover on your 800 to expose the memory boards, you will see that the plastic case sits in a track that doesn't allow the memory board to move. When you take off the plastic and put the PC board back, you will see that the board can wobble around. Typing on the keyboard sends vibrations throughout the entire computer. This can cause the unhoused boards to wiggle back and forth, sometimes disturbing the connection between the board the socket. On the new 800's, the memory board isn't cased in plastic, but Atari has installed a guide to hold the memory in place. The second thing the plastic case does is act as a "heat sink, " that is, it allows the heat to dissipate evenly inside the computer.

Q. My keyboard worked fine until I bought Defender. Now I am having problems. --Bob Day, IL

A. The keyboard on your computer can only take so much. When saw the way to activate the smart bomb on Defernder, I knew there would be problems. People play Defender in my stores, and they slam their hand down hard on the space bar to set the smart bomb off. Even though the keyboard can take a lot of pounding I recommend that you be very gentle when using Defender or it will cost around $130.00 to get a new keyboard.