> -----Original Message----- > From: Tony Duell [mailto:[email protected]] > Sent: 04 November 2018 12:42 > To: [email protected]; Jarratt RMA <[email protected]>; General > Discussion: On-Topic and Off-Topic Posts <[email protected]> > Subject: Re: Datasheet for a NEC Chip in DEC Professional 350 > > On Sun, Nov 4, 2018 at 12:37 PM Rob Jarratt via cctalk > <[email protected]> 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....
I have been trying to find what is driving this path in the logic and this chip was the only one I for which I couldn't identify the pins, but it seems that from this datasheet (https://datasheet4u.com/datasheet-pdf-file/1098405/NEC/UPD7201/1) they are all inputs and not outputs. So I need to look again for an output pin that is driving this signal. Thanks Rob
