On Sun, Nov 4, 2018 at 12:37 PM Rob Jarratt via cctalk <cctalk@classiccmp.org> wrote: > > I have posted previously about a DEC Pro 350 I am trying to get working > again. At the moment it seems to be constantly resetting the CPU. > > > > I have traced one possible path for the cause of this back to a NEC chip for > which I cannot find a datasheet. It is a 40-pin DIP it is marked "NEC Japan > 8239K6 D7201C". All I have been able to find is more modern USB host > controllers.
Almost certainly a uPD7201 multi-protocol (asynchronous and synchronous) serial chip. I have an NEC data book with it in if all else fails but a google search for 'uPD7201 datasheet' (no quotes) found sites with the data sheet to download as a .pdf file. Quite why that should reset the machine is beyond me.... -tony
