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PDP 11/45, Part 3

Hi All;
I have another problem, after the system is running about 5 to 10 minutes, it quits running..
I have not located the problem as of yet.. I am going to first try my memory board, as that doesn't have a fan cooling it off..
Then get some Cold Spray and see if I can Isolate it to a board and a section, then to an Ic..
I pulled the M7800 Board, and so this is Not the problem..
I am Running Don's ZZ program, starting it at 173000, from the Console, since there is no I/O as of yet..
I do have Output from the computer, and so that make two boards with an Output and no input..
And so that has to be traced back, as well..

THANK YOU Marty
 
Hi All;
I have one Serial I/O Board working (M7800) !!!!!!
One of the other ones, I can Modify, Now that I know, what connections and Ic's are involved..
I also, found that The M7800 Board that Blew up the PDP 11/40 is Laid out different, than my other two Boards..
And since it has been Modified, I think for safety sake it will revert it to a Parts Board, Until I can Determine, what all modifications have been made to it..
I ran the PDP 11/45 for 7777 Octal passes of Don's "ZZ" Test program..

THANK YOU Marty
 
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Hi All;
I am still having some problem(s) with the (I think) Input It will display what I type, but quite often It is wrong.. I have slowed down the Baud Rate from 9600 to 1200, and that has helped quite a bit.. But not completely.. It seemed like if I really slow it down to 110 Baud, that it gets it Completely right..
One possibility, is that the USB to Serial converter, does not do a full swing for the RS-232 standard, and so it gets confused..
My New to me PC does Not have any Serial Ports, only USB..
I can get out my old computer and use its Serial Com port and that will tell me if my Theory is correct or not..
I have tried it with my other Computer, and the Serial Com Port works flawlessly.. It show exactly what I have typed and it responds correctly to the commands..
I have tried it at 1200 Baud and at 9600 Baud, and it works on either speed..
So, I need a True Com Port on Asus Computer..

THANK YOU Marty
 
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This is where having an older laptop comes in really handy. It's portable and you got all the necessary legacy connections.
 
Hi All;
Next, Thanks for Your reply..
In my case the two laptops that I have Don't work with Windows, and they Don't have true Serial Ports, more importantly..
I need a fairly Fast Desktop or Floortop model, with true Serial ports..
For now what I need to find is a PCI or is it PMS to Serial Com Controller Card.. I don't have any at the present..

THANK YOU Marty
 
I've had good luck with the Dell Latitude D630 as a general toolkit laptop, hardware serial port, decent size and weight, supports SATA hard drives / SSDs and they are removable to make supporting multiple OSes a breeze. Look for the 2.5 or 2.6Ghz Core2Duo model, as they have the most cache. Supports up to 8GB of RAM, though 4GB is more common. And they can be found used on eBay for under $100, though you may have to add a hard drive and power supply for that price. They will run Windows 7 without too much hassle, all the needed drivers (except maybe wireless) are included on the Windows 7 disk. They make good Linux/bootable CD systems as well.

The D620 is also a decent choice, pretty much the same chassis, just the previous generation of CPU/chipset.

Intel graphics are more reliable than Nvidia on these, though.
 
Marty said:
One possibility, is that the USB to Serial converter, does not do a full swing for the RS-232 standard, and so it gets confused..
Click to expand...

Another option would be to see if perhaps the M7800 board uses the old MC1489 RS232 receiver chip. That chip has a response control for each input. You could apply -5 V through a 15K or 20K resistor and move the hysteresis switching threshold to about 2 volts instead of the 0.8 Volts if the bias input is left open. That should work well for a TTL switching signal. It will also work fine with the normal +/- 10V swing of a proper RS232 signal.

See sheet 7 of the MC1489 spec sheet for more info on how to move the threshold.
-Dave
 
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Marty said:
Hi All;
HoJoPo, Thank You for the Heads up on the Dell D620, Now to find a couple of them in my Area..

THANK YOU Marty
Click to expand...

You're welcome. I found a few D630's on Craigslist in my area, but they're more expensive than eBay. Pacific Geek also sells D620/D630 refurbs, but with the lower spec processors: http://pacificgeek.com/

I'm a network engineer, so a good hardware serial port comes in handy, some of the network gear I support (Brocade... ugh) doesn't like certain USB to RS-232 adapters. I've had good luck with the FTDI chipset ones though.

I have a USB to four port serial adapter with the FTDI chipset that I'm using to interface a Raspberry PI to a few vintage systems for shell / Internet access. Makes a really cheap, really versatile terminal server for under $100. The new B+ model of the Pi has four USB ports, making it easy to put mouse, keyboard, USB to serial and wireless networking on it without requiring a hub. Heck if the mouse plugs in to the keyboard, you could even have 8 serial ports without a hub. It would be a great way to put wireless networking on a PDP-11, you could even dedicate one port to SLIP or UUCP, and use the other ports for login or console on the PDP-11.
 
Marty said:
One possibility, is that the USB to Serial converter, does not do a full swing for the RS-232 standard, and so it gets confused..
Click to expand...

I have seen this, too, with my DEC equipment, as well as with various vintage computers. It has been hit-or-miss for me, with my Apple IIC+, Apple IIGS, and TRS-80 Color Computer working excellently with my USB-to-RS-232 converter, but other S-100 systems and my DEC system not liking it at all.

Just my 2 cents worth... You are not alone with this phenomenon.

smp
 
Hi All;
SMP, Thank You for the Encouragment..
"" I have seen this, You are not alone with this phenomenon. "" I am very surprised, and I am so glad, I thought it was just me and my Dec Equipment.. That I had not gotten all of the Bugs out of the System.. And I had thought I was going to have to use my Altair 8800 as a Go-between, between my Asus Pc and my PDP 11/45 Dec.. That sure cuts that, Idea..
DaveM, I did not see You Response till just a moment ago, That sounds like something that I can Try.. Thank You !!!
"" Another option would be to see if perhaps the M7800 board uses the old MC1489 RS232 receiver chip. "" It Does, as well as the M7856, They both use the 1488/1489 Rs 232 chip sets..
THANK YOU Marty
 
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dave_m said:
Another option would be to see if perhaps the M7800 board uses the old MC1489 RS232 receiver chip. That chip has a response control for each input. You could apply -5 V through a 15K or 20K resistor and move the hysteresis switching threshold to about 2 volts instead of the 0.8 Volts if the bias input is left open. That should work well for a TTL switching signal. It will also work fine with the normal +/- 10V swing of a proper RS232 signal.

See sheet 7 of the MC1489 spec sheet for more info on how to move the threshold.
-Dave
Click to expand...

Thanks for pointing this out Dave. Something more that I didn't know ...
 
Hi All;
The PDP 11/45, just died, or there is almost no Response from the Front Panel Switches..
My best guess, is something with the Timing Board, But, at this point it could be anything..
The fingers were cleaned on Saturaday, when it failed in this way, and the Timing Board Fingers were the worst..
I can do the Cardboard-Alcohol thing, on or in the various slots..
Here is a picture of the Future Data Paths Board, which will have Lots of LED's..

003.jpg

THANK YOU Marty
 
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Hi All;
All of the Power and Ground connections are wired in the Data Paths Board.. Also, I have made it so that it will use both Wide and Skinny 24 pin Sockets for the 74S181's.. Now to start the Real wiring..

002.jpg

THANK YOU Marty
 
Hi All;
I have somewhat determined that the Timing Board is not working.. I don't know at this point, If it is the Board itself, or If another Board Is causing it to stay in a Halt mode..
I have it on an extender card and my maintenance board is plugged in as well.. I am having trouble Telling what the Maintenance is showing, so it might need to be on an extender card as well..
The Crystal and associated parts are fine, so its at least got some life to it..
The switches are working and sending their signals to the UBC Board.. Which still seems to point to the Timing board again..

THANK YOU Marty
 
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Hi All;
While looking for the links from my old postings, for the AC LO and DC LO signals for AtomicThumbs on his 11/73, I stumbled on some of my old postings for problems on my Timing Board.. And so, I am going to re-read that section, and hopefully it will or can give me a clue as to where to start or what to do on my or with my Timing Board problem..
THANK YOU Marty
 
Hi All;
I think I have found something, it may not be the problem, but it still needs to be fixed..
On the Timing Board, there is a signal, PHKA Stop T1 L, which is H(igh).. And while I am at it I will look at the other PHKA signals..
I am taking out Everything and Looking at the Bottom of the Board, Maybe Something got "Toasted" when I had the Lamp Short..

THANK YOU Marty
 
Hi All;
I DON'T HAVE A CLUE !!!!!
But, it now Works !!!! What I did is traced the wire from the "" PHKA Stop T1 L.. Signal, and I have been there before, as It has a Red Insulator on it, I cleared the area of surrounding wires, by pushing them all back from the pin, and pushed the red insulator down further on the pin.. Straightened out a few pins here and there, but nothing was touching anything else..
"" I am taking out Everything and Looking at the Bottom of the Board, Maybe Something got "Toasted" when I had the Lamp Short.. "" No, all is OK..
And now it works again !!??!!???? Next, I will add my M7800 I/O card..
It is now Running Don's ZZ Program, and the M7800 Board works, both ways Input and Output.. 7777 passes, on Dons ZZ program..
I am Not going to work on the other I/O Board for awhile, and just Savor having it running, and working on/with small programs..
THANK YOU Marty
 
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