4 Nov
2018
4 Nov
'18
1:55 p.m.
There was a NEC CPU upgrade kit, one used to replace the stock CPU, is this
what you're talking about here? If so, I believe there was a battery that
went with the chip. If the battery is dead the chip would not work. Or am
I totally remember this wrong?
b
On Sun, Nov 4, 2018 at 4:36 PM Ed C. via cctalk <cctalk at classiccmp.org>
wrote:
Just had a look to this manual:
http://www.bitsavers.org/pdf/dec/pdp11/pro3xx/EK-PC350-TM-001_Professional_…
5.2.3.4 Power-Up Self-Tests, this section mentions the existence of rom
containing basic power up tests. I assume you are not even getting there
and your system fails to execute from this rom and report any errors on
screen?
In such case, A) is your cpu working? B) Is the rom code correct?
On Sun, Nov 4, 2018 at 10:11 PM Rob Jarratt <robert.jarratt at ntlworld.com>
wrote:
system
-----Original Message-----
From: Eduardo Cruz [mailto:edcross at gmail.com]
Sent: 04 November 2018 13:47
To: rob at jarratt.me.uk; Rob Jarratt <robert.jarratt at ntlworld.com>;
General
Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Cc: Tony Duell <ard.p850ug1 at gmail.com>
Subject: Re: Datasheet for a NEC Chip in DEC Professional 350
A constant pulsing reset is usually a watchdog at play. Hardware
watchdogs
> are usually implemented in systems to reset everything should the > not meet one specific criteria: eg cpu touch
one memory address before
X
> amount of time, or pcb voltage lower than X
volts, etc.
>
> Watchdogs are also usually found as software routines executed by the
cpu
> also looking for specific conditions. These
rarely issue a reset
hardware
signal,
the
just restar the program.
It looks to me like the reset is every 10us. I don't know how long the
watchdog is likely to be, the technical manual I have doesn't seem to
mention it in the section on the reset logic. I am still trying to find source of the signal that seems to be in the
"wrong" state.
Regards
Rob