28 Oct
2018
28 Oct
'18
11:10 a.m.
-----Original Message-----
From: Tony Duell [mailto:ard.p850ug1 at gmail.com]
Sent: 28 October 2018 18:04
To: rob at jarratt.me.uk; Jarratt RMA <robert.jarratt at ntlworld.com>; General
Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: DEC 8640 Pinout
On Sun, Oct 28, 2018 at 5:53 PM Rob Jarratt via cctalk <cctalk at classiccmp.org>
wrote:
I've sent the data sheet by private e-mail.
Have you looked at the Pro380 printset on bitsavers? The reset input on the
J11 chip in that machine comes from the DCOK pin on the power supply (Pin
1 of the PSU connector). It's also buffered by an 8640 for other bits of the
systen. I would not be surprised if the Pro 350 is similar.
Are you_sure_ the DCOK pin on the power supply is stable and not
oscillating?
Thanks for the datasheet. I have to say I am not totally convinced that I have correctly
identified the reset pin on the F11 because there seems to be a lot of logic behind it.
This particular path I am pursuing now seems a bit more promising though. I have not
checked the DC OK pin yet as I wasn't sure which one it was and I was hoping my
tracing would take me back to the PSU, but I haven't reached it yet. I suppose I have
been assuming that the LED means it is OK, but perhaps it isn't. Hopefully this 8640
will take me closer. When you say it is pin 1 on the connector, which side are you
counting from?
Thanks
Rob
I am trying to trace the reason why the CPU on my Pro 350 is
apparently being constantly reset. I have reached a DEC 8640 chip.
Does anyone have a pinout for it, perhaps even a datasheet, so I can
understand what it is supposed to do and whether the pin is an input or an
output?