3 May
2021
3 May
'21
11:23 a.m.
Sadly my machine is not at the point where I can attach a console of any kind. The CPU is
being reset every 13us by a bus error. I am having trouble working out why though. I have
got as far as working out that is the CT2 TIME OUT signal, but just why that is active
isn't entirely clear to me. It would help to have a working machine to compare it to!
Regards
Rob
-----Original Message-----
From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Bjoren Davis via
cctalk
Sent: 03 May 2021 18:30
To: cctalk at classiccmp.org
Subject: Re: Documentation for F11 Chipset?
I recently brought a PC350 back from the dead.
A good source of documentation for the F-11 is that for the 11/23 and
11/24 (e.g.,
http://bitsavers.org/pdf/dec/qbus/Digital_Microcomputer_Processor_Hand
book_1979_80.pdf
chapter 3 "LSI-11/23 Processor" or
http://bitsavers.org/pdf/dec/pdp11/1124/EK-11024-TM-
001_PDP11_24_System_Technical_Manual_Jun81.pdf)
Thanks for the tips, I will take a look.
The first thing I'd do is to attach a "console terminal" cable (a cable
attached
to the printer port with pin 9 pulled to ground -- pin 8). DEC makes such a
cable called BCC08 but I just made one myself.
Sadly my machine is not at the point where I can attach a console of any kind. The CPU is
being reset every 13us by a bus error. I am having trouble working out why though. I have
got as far as working out that is the CT2 TIME OUT signal, but just why that is active
isn't entirely clear to me. It would help to have a working machine to compare it to!
Regards
Rob
Then use a terminal program at 4800 to send a break
and see if you get the
ODT prompt.
In my case I didn't get such a response. It turned out that the leaky battery
had destroyed the "EPCI" at E155 (the async serial chip for the
printer/console terminal port). I swapped the EPCI at E154 (the keyboard
async serial chip) and I was able to at least talk to the ODT. I then bought a
replacement EPCI on eBay and I was on my way.
Good luck!
--Bjoren
On 5/3/2021 12:16 PM, Zane Healy via cctalk wrote:
documentation there.
>
> Zane
>
>
>
On May 3, 2021, at 3:19 AM, Rob Jarratt via
cctalk <cctalk at classiccmp.org>
wrote:
I have
gone back to trying to fix my DEC Professional 350. I have a
printset for the machine now. I think the CPU is being constantly reset.
Is there any documentation anywhere on the F11 chipset? Bitsavers
only seems to have the later J11.
Is the Sunsite archive still online? I seem to
recall there being some