READERS' FEEDBACK

The Editors and Readers of COMPUTE!

64 Screen Problems

I own a Commodore 64 computer. While I am quite pleased with its performance, there is a problem. Any program that uses the BASIC commands GET or INPUT causes severe interference in the form of many white (silver) horizontal lines which shoot across the color TV screen.

I also purchased some software (namely The Word Machine and The Name Game) from Commodore and these programs exhibit that same, quite annoying, problem. I might add that three friends here in Albany who also own the C-64 have the exact same problem. I have heard that Commodore replaced a video chip in the later models (of which mine is one) and that there are problems with this new chip.

My question is: will Commodore solve what may be a very large (in number of computers) problem? My warranty is close to expiration.

Donald G. Weiser

This is probably the question we're asked most about the Commodore 64. The problem that you are referring to has come to be known as "sparkle."

The problem starts with the 64's character ROM, and the sparkle is caused by the way the 64 generates its characters to put onto the screen.

However, this problem can be more than a mere inconvenience in the early machines. It can cause difficulties with some programs, especially games. When utilizing the advanced 64 Sprite features (user defined, moveable objects), the sparkles can cause the computer to register a sprite collision when none has occurred.

There are some solutions. One is to make a few hardware modifications inside the 64, but this solution is frowned upon by Commodore, and may void your warranty. Another is screen relocation. It is said that if you relocate the screen memory into another area of RAM, the sparkle will disappear.

As for the number of units plagued by this problem, Commodore's estimate is five percent. It should be noted though, that almost all of the early models had sparkle, and as of this writing the problem is apparently still not solved. As a matter of fact, COMPUTE! recently purchased two 64s for testing purposes, and one has a very severe "sparkle" problem.

In answer to your question on repairs, Commodore has no set policy in this area. For units that are under warranty, Commodore says that it will attempt to repair anything with which the customer is dissatisfied.

Concerning units out of warranty, Commodore had no comment. However, a number of computer dealers and repair centers have stated that they will install the new or updated character ROMs if they can get them from Commodore. Commodore has said that they have not yet decided whether or not they will make the new character ROMs available to the service centers.