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Build your own PDP 8I, Part 3..

M

Marty

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Hi Marty,

For you information the first 2 links you have posted here go to the HUGE 404 Broken link page.

However the 3 and 4 links work.... AND if you open the Part 2 link and click on the PDP-8-book link it works from that page.

As the lucky owner of a original genuine DEC PDP-8i I can fully understand the preference to build a machine out of individual chips rather than an FPGA.

regards
David
 
what form factor PCB/s are you building this 8i. Are you using wire wrapping or ?

what form factor PCB/s are you building this 8i. Are you using wire wrapping or ?

Hi Marty,

Sorry to maybe ask questions that you have already described in earlier postings.

I am curious are you building your 8i in exactly the same form factor individual pcb cards, as the original DEC 8i ?

If so what are your plans for making a backplane ?

Be interested to know.

and are you doing plated though hole pcbs or are you wire wrapping your entire machine ?

keep up the good work,

regards
David
 
Hi All;

I think I got the first two links fixed..
Dave, I am Wire-Wrapping the Entire thing, on a mostly single Wire-Wrap though hole non-plated Board..
I will eventually Wire-Wrap the memory and the I/O on another Board..
"" I am curious are you building your 8i in exactly the same form factor individual pcb cards, as the original DEC 8i ? ""
NO !!!
"" If so what are your plans for making a backplane ? ""
It doesn't need one, it's all on a single Board..
Look at the pictures that I have posted..

THANK YOU Marty
 
Marty said:
Hi All;

I think I got the first two links fixed..
Dave, I am Wire-Wrapping the Entire thing, on a mostly single Wire-Wrap though hole non-plated Board..
I will eventually Wire-Wrap the memory and the I/O on another Board..
"" I am curious are you building your 8i in exactly the same form factor individual pcb cards, as the original DEC 8i ? ""
NO !!!
"" If so what are your plans for making a backplane ? ""
It doesn't need one, it's all on a single Board..
Look at the pictures that I have posted..

THANK YOU Marty
Click to expand...


Hi Marty,

I own an original DEC 8i.

I had the complete machine in 3 by 19" racks.
due to space limitations for storage, I had removed the machine from the racks, and it had been stored in a back shed annex to my car garage.
However during house move the 8i CPU cage /backplane and cards has gone missing.

till searching for it.

The rest of the machine I have, inc front panel and lots of spare boards.

I have a post here in this forum about it.

Worst case, as i said in that post, I will make a replacement backplane, and hunt for original boards to populate it.

I have an 8k extended memory rack so that part may end up being my main memory, should i not find enought spares.

regards
David
 
Marty,

I have just 'bashed in' the schematics into LOGISIM - I am finding errors all over the place!

Now the job of finding (and fixing) the errors begins...

I have attached the schematics as they are now.

Well - one of them - I am having problems with the other (it may be too large?) - yes it is!

Marty - can you PM me your e-mail address and I will send it to you if you want it.

Dave
 

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Hi All;

Dave, Thank You for doing this..
"" I have just 'bashed in' the schematics into LOGISIM - I am finding errors all over the place! ""
I would Love to see the Timing Diagram, before You begin to make any changes, If Possible..
You have put in the I/O (TTY), which I have NOT even gotten to, I am a long ways from putting that into the Mix..
But, having said that, I am and Would be interested in what result You get with or from it.. Your Logisim output..
And Remember that on this my Second Version, I have made many changes and at this point I don't know IF those changes will make any difference, or not in the basic running of the PDP 8i Clone..
Once I hopefully get it running, I MAY be able to take alot of those changes out without it having any adverse affect on the Running of the unit..
I have just received the 18 pin sockets, So I can continue wiring now..

THANK YOU Marty
 
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daver2 said:
Marty,

I have just 'bashed in' the schematics into LOGISIM - I am finding errors all over the place!

Now the job of finding (and fixing) the errors begins...

I have attached the schematics as they are now.

Well - one of them - I am having problems with the other (it may be too large?) - yes it is!

Marty - can you PM me your e-mail address and I will send it to you if you want it.

Dave
Click to expand...

I'd like to see your schematic as well. I'll PM you my email. Any chance of you putting the LOGISIM files anyplace?
 
Hi All;

DDS, I don't know if it was a mistake, or what, But I got a copy of Your Email to Dave..
So, if it was You need to ReSend it to Dave..

THANK YOU Marty
 
Marty said:
Hi All;

DDS, I don't know if it was a mistake, or what, But I got a copy of Your Email to Dave..
So, if it was You need to ReSend it to Dave..

THANK YOU Marty
Click to expand...

I have enough posts to qualify as a "Senior Member" but other than doing basic posts I'm still a noob. That was the first or second PM I've done and didn't see how to CC you. OTOH I didn't want to ask Dave to send me a copy of the schematic he made from the files you provided without letting you know. So I sent the PM to both of you.
 
Hi All;

DDS, I was hoping that was the case, or something like that..
But, I wanted to make sure, and not make any assumptions..
And Thank You for Your thoughtfulness..

THANK YOU Marty
 
Hi All;
Al, Thank You for that Interesting Link..
Way above my price range..
But, I have Ordered a Front Panel PCB, from Oscar, and it's on it's way.. Thank You Oscar, for being so kind and generous..
Hopefully, I can figure out how to make it, eventually work on my System.. Once, I get everything else figured out..

THANK YOU Marty
 
Marty and DDS,

PM sent to each of you with Version 0.2 of my LOGISIM simulation of the PDP-8 LD12 attached (a work in progress!).

Regards,

Dave
 
Hi All;

Dave, THANK YOU for the files, I will look at them tomorrow, and see if I can get them to display correctly in Logisim.. Before offering any suggestions..

THANK YOU Marty
 
No problem.

I use the 74151, 74163 and 74174 circuits out of the 7400-lib library and a 74181 circuit from a different library. I may also have fixed an error in the 74174.

I can PM you a copy of the libraries I use if you wish.

Incidentally, I have found a source of most of the 74xx and RAM chips locally so I may purchase them.

Regards,

Dave
 
Hi All;

Dave, Thanks for Your prompt reply..

"" I may also have fixed an error in the 74174. ""
What Error ??????????
Even though I am using the 74175's in this go around, It would be good to know, If it is something I need to be aware of..

THANK YOU Marty
 
Marty,

Not an error in the 74174 IC itself - but the 74174 library that comes with LOGISIM. The clock input was configured as a high level rather than a low-high edge (if I remember correctly).

So not a problem you need to consider with the 'physical' implementation...

Dave
 
Hi All;

Dave, OK.. Thank You for setting me straight on that.. Before I attempt to try it on the Simulator.. Is that fixable ??

THANK YOU Marty
 
Hi All;

Dave, can You send me Your Library files, I don't know IF I need them or not..
I started Logisim, but, I have no idea what to do or how to do to make it work.. It might be already working, I don't know how to tell..

Here is the latest in pictures.. The first picture is my wiring progress, and the last two are the top, the very last picture is the final layout..

001.jpg 002.jpg 003.jpg

THANK YOU Marty
 
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