piskacrj@mentor.cc.purdue.edu (Robert J Piskac) (11/12/90)
I am posting this for a friend. Please do not reply to me. Send replies to : ab245@cleveland.freenet.edu (Sam) =============================================== I have been real busy around here and I am have been having a problem with one of my 128. Maybe you have heard or seen this before, I hope so. I just out of the blue decided to load up the Desterm on the 128 that I don't usually work with. Well was I surprised to find out that it will not give me the same 40 columns screen while I'm in the 80 columns mode like my first 128 does. Same program and same (disk) that is. What happens is I get 3 columns of gray vertical lines that run from the top of the screen down to the bottom of the screan instead of just getting the two modem prompts OK OK like I do with the first 128. I pulled the 128 open and found that where there is normally just one ic chip in socket U29 that should be a HD7406p this 128 has that ic pluss a board piggy backed on top of it with a strainge ic and cap. The ic is a DM74LS74Am SM 8521 and there are 4 pins soldered from this board down to the U29 IC one pin on all 4 corners with a wire going up to the clock ic U28 and a wire going ocer to where the x-tail is. Anyways I have not found out what this extra chip is for yet but the hole modification is all factory. Ther is no way that anyone could of soldered this in after the unit was built. It was a 100% true stock 128 never been opened by anyone other than me and to desolder and take this board out the board would have to be destroyed to get it out. It was soldered in before the steel box was ever installed around the video section on the board. Have you ever seen or heard of this before??? It looks like as if Commodore was doing some kind of experimental job on this and as far as I can tell at this point the U28 is the RAM chip for the 80 columns mode, now with this other ic on top of it I don't know if they were trying for more ram drivers for the 80 columns or what they were doing. I don't realy think I'll ever use the 128 with anything like that SUPER 8 program or any cad program and would just like to get it to work with the 40 columns in the 80 columns mode as I do with my first 128 so they are both the same. Got any ideas at all on this??? I have seen over 100 of the 128 and never seen this before at all, I woulder just what it's for...Sam --