euloth@dalcsug.UUCP (George Seto) (02/12/88)
I am posting this for a friend who has no access to the net. In the RTC C-Link interface, there are three IC's. They have had the part numbers sandpapered off. HE is trying to repair it and needs to know what the chips are. Can anyone help? Thanks in advance. . -- ******************************************************************************* * euloth@dalcsug.uucp || Disclaimer: All opinions are my own unless other- * * /\/\/\/\/\/\/\/\/\/\ || wise noted. * ****AKA: Atari Nut*************************************************************
elg@killer.UUCP (Eric Green) (02/15/88)
in article <337@dalcsug.UUCP>, euloth@dalcsug.UUCP (George Seto) says: > I am posting this for a friend who has no access to the net. > > In the RTC C-Link interface, there are three IC's. They have had the > part numbers sandpapered off. HE is trying to repair it and needs to > know what the chips are. Can anyone help? Thanks in advance. The big chip is either a 6820 or a 6821. I bet 6821 (pinouts are identical between the two, fanouts are different from the i/o port). It's the one that's most probably gone. The TTL closest to the edge connector is a open-collector high-voltage buffer that most probably is still good unless your friend really fried things. I forget the exact number, alas, it's been awhile. I suspect either a 7407 or its non-inverting mate. Finally, the TTL closest to the computer is that old standby, the 74LS30, the 8-input NAND gate used so often in these "transparent" interface thingies. A long long time ago, right after RTC declared bankruptcy and went under, I blew up my computer with that "#$"$% stock Commodore power supply, C-LINK included (took $40 worth of chips to rebuild everything... practically every MOS chip in the entire computer was fried to smithereens). I had to do it the hard way... by looking at what lines went where (stripping the board helps), and then matching it against the TTL databook. The 74LS30 was a piece of cake, it has a pinout that's singularly distinctive (8 inputs, 1 output? sheesh!). The idiots thinking that filing the number off of it was a deterrent were either brain dead or just weren't thinking... I suspect the former, considering that RTC went under. No wonder. As for the big chip, what the hell could it be besides a PIA or VIA or CIA? It's easy enough to tell the difference... a PIA has 3 chip selects, a VIA two, a CIA only 1. Sheesh. Anyhow, pinouts matched with a PIA. Case closed, mystery solved. Those people at RTC musta had noodles for brains, because I make no bones about being software, not hardware, and if even I could figure it out... -- Eric Lee Green elg@usl.CSNET Asimov Cocktail,n., A verbal bomb {cbosgd,ihnp4}!killer!elg detonated by the mention of any Snail Mail P.O. Box 92191 subject, resulting in an explosion Lafayette, LA 70509 of at least 5,000 words.