From: Ethan Dicks (ethan.dicks_at_gmail.com)
Date: 2007-03-28 03:16:45
On 3/27/07, Anders Carlsson <firstname.lastname@example.org> wrote: > Bil Herd on behalf of Jeri Ellsworth wrote: > > > The two resistors on the chip mark it as a TED where the test mode pins > > were higher impedance than predicted by the chip designers and a strong > > electric field would freeze the counters. > > Oh, those are resistors? With my limited electronical knowledge, I really > thought they were diodes too. Those really look like two diodes to me - glass, orange with a black band... diodes will act a bit like resistors in the sense that there is a voltage drop across a diode junction, but they are not like resistors in all cases - you'd have to look at the spec sheets and know (or measure) the current in circuit to calculate how it will behave. > Bil writes that he added an 8-bit latch "8529 or something like that", Lots of MOS parts are in the 85xx family. > while I observe two chips named 8329, assumed to be RAM. Ethan suggested > that U4 should hold a 82S100 or similar. I would suggest that the RAM chips are from the 29th week of 1983, not that they have a part number of 8329. Given that the board is stamped Aug, 1983, the dates on the RAM chips seems reasonable. I would think that the DRAMs are known as IMS 2629P-15, for "INMOS" and P for plastic package, and 15 for 150ns. The 2629 isn't an obvious part number, but Inmos has a 2620 and a 2630 in the right size range... http://www.batnet.gliwice.pl/chipdir/f/dram.htm It's certainly not as common a part as a TI4416, but there were plenty of by-4 DRAMs after 1982. > I need to get access to an EPROM reader/burner to dump those chips > safely. The 2764:s I could read off a C64 cartridge with EPROM slots, > but I don't think I have anything to read the 27128. If you have anything with a 27256 socket, the 27128 is like that with one less address line. Cheers, -ethan Message was sent through the cbm-hackers mailing list
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