Path: utzoo!attcan!uunet!zephyr.ens.tek.com!orca.wv.tek.com!pogo!rickc From: rickc@pogo.WV.TEK.COM (Rick Clements) Newsgroups: comp.sys.cbm Subject: Re: changing character color Message-ID: <9985@pogo.WV.TEK.COM> Date: 22 Oct 90 17:13:37 GMT References: <14474.271f60da@max.u.washington.edu> Reply-To: rickc@pogo.WV.TEK.COM (Rick Clements) Organization: Tektronix, Inc., Wilsonville, OR. Lines: 22 In article <14474.271f60da@max.u.washington.edu> scott@max.u.washington.edu writes: >> My father's Commodore 64 has quite a strange problem. When the >> characters on the screen scroll up, the color of the characters changes! : >> We thought that perhaps the color-ram was broken, but the fact that >> the colors stay the same when the screen does not change, indicates that >> the video processor can read the ram correctly. With a basic test >> program however, with which we write a value into the color-ram, and >> read it back again, the value we read back is often not correct. >Sounds like a classic case of the power supply going faulty. Try borrowing >a working power supply for the C64 from a friend and see if that fixes it. As long as people are guessing ... I think it is related to the RAM. It could be an address or data. The data and address path is a little different for the CPU and video chip. The CPU has to read and write the data when it scrolls. I would try switching power supplies because it is easy. But, I don't see how it would cause this problem. -- Rick Clements (RickC@pogo.WV.TEK.COM)