That's not likely to be the PLA. If the PLA was bad you would expect that whole blocks of memory would be bad at once. Check the line drivers and timing circuitry. These would be more likely to produce random errors. But first, check the power supply and voltage regulators, check for proper voltages, loose connections, and overheating voltage regulators. These can all produce the same errors. On Sun, 25 Jul 1999, [ISO-8859-1] Marko Mäkelä wrote: > Hallo Marc, > > On Sun, 25 Jul 1999 MSchnei685@aol.com wrote: > > > Gudday, > > > > congratutlations on your comprehensive collection of material on the computer > > gems of the 1980's: Commodore's 600 & 700 Series. So far, I found everything > > I needed here ;-). > > > > Unfortunately, my Commodore 610 (Serial #1466) seems to have deteriorated, by > > aging, I suppose: strings stored in memory are not read properly, e.g. the > > filename in load-commands is garbeled randomly with Pi-characters. These have > > the memory code of 0xFF, so obviously the data bus read is hi-impedance or > > the data is not stored and/or refreshed properly in the dynamic RAM > > (Bank1&2). So I suspect the system-decoder-FPLA 82S100 (U18, Commodore > > Part#906114) to be in doubtful condition. I plan to replace this by a PAL16L8 > > with adaptor socket - I have the logical equations, but am not sure if they > > are correct. If you are interested, I might contribute these parts > > (documented PAL and adaptor layout). > > > > I'd like to get your advice on this topic - do my observations make sense, or > > is there another known bug in the system producing these symptoms? Ullrich > > von Bassewitz suggested the video RAM might be affected, but I don't see how > > that would affect stored strings. > > > > Best regards & greetings from Brunswick (Germany), > > Marc > > > > I'm forwarding this to the cbm-hackers mailing list, since I don't know > anything about the 610 (except the documents that have been uploaded to > ftp.funet.fi). > > I don't think that it is the PLA. If there is a data bus multiplexer, I'd > have a look at it first. But of course, I'm interested in the PLA > equations. > > BTW, is "Brunswick" the English spelling of "Braunschweig"? That was > where the German headquarters of Commodore were located, right? > > Marko > > - > This message was sent through the cbm-hackers mailing list. > To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tcm.hut.fi. > - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tcm.hut.fi.
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