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Build your own PDP 8I, Part 3..

Marty,

I have made a few 'tweaks' today and run some quick diagnostics withe no ill effects.

I have removed signal A0 from the calculation of CIN (replacing it by a logic '1').

I have used the MA register (instead of PC or MB) in the calculation of the Effective Address (EA).

I have implemented the logic for NMR+DIRECT*(DCA+JMP+JMS).

I have also done a quick check of the use of the An and Fn signals and their use looks consistent with my state diagram.

I will ZIP up the latest LOGISIM circuit file shortly (Version 0.5 dated 18th october 2015) and attach it to this post. Done.

Dave
 

Attachments

  • PDP8-LD12.circ.zip
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Hi All;

Dave, Thank You for Your additions and Modifications..

"" I have removed signal A0 from the calculation of CIN (replacing it by a logic '1'). ""
I am not surprised with the removal of A0, I would tie it to a pin next to it, instead of to a logic "1", but that is personal preference..
"" I have used the MA register (instead of PC or MB) in the calculation of the Effective Address (EA). ""
Good, then I can implement it..
"" I have implemented the logic for NMR+DIRECT*(DCA+JMP+JMS). ""
Great, I will implement this as well.. I will await Your Schematic, to make sure I have the correct implementation, before I will try and wire this..
"" I have also done a quick check of the use of the An and Fn signals and their use looks consistent with my state diagram. ""
This will hopefully, reduce the changes necessary, in the future..
Dave, Did You see my Private Message ??

THANK YOU Marty
 
Marty,

New ZIP file added.

I haven't run extended diagnostics on this yet (just a quick blast). I will have to run the diagnostics for a reasonable time next weekend. The latest release did, however, make its first move in Blitz mode on CHEKMO-II (albeit somewhat slowly due to the nature of software simulation).

Yep, I got your PM. I agree - the 74133 is about the only device I am having trouble sourcing. I have access to a very large component purchasing group at work - so I may avail myself of their services!

Dave
 
Hi All;

Dave, Thanks for Everything..
On another note, I am wondering, since there are other A0 points, What and Why did You eliminate A0 in the Calculation of CIN ??
Not that I question Your Logic, But, I am curious as to why it is eliminated.. I figure that since You have said that "" I have also done a quick check of the use of the An and Fn signals and their use looks consistent with my state diagram. "" And so a part of this was/is eliminating of this particular A0 signal to make the signals agree with the state Diagrams..
I just want to know How You did this, so I can do it and see the process, part of my learning..
I have downloaded Your file, I will look at it tomorrow..
"" Yep, I got your PM. I agree - the 74133 is about the only device I am having trouble sourcing. I have access to a very large component purchasing group at work - so I may avail myself of their services! ""
I would suggest looking for an alternative to the 74133, I have a few Extra's, but not a whole bunch..
Would Substituting two 74F30's (or 74AS30's) followed by a 74F08 work ?? Having 6 bits on each of the 7430's.. I'LL have to see tomorrow what is available, I know 74F08 is available, but, I am not sure what fast IC is available for the 7430's.. So, to make the delay of these gates equal to the delay of one plain or LS gate (74133)..
Also, what about the 7451, I have plenty, should that be converted as well to two 7408's and a 7402 ?? That way all of the Ic's are easily obtainable type of Ic..
"" I have access to a very large component purchasing group at work - so I may avail myself of their services! ""
Good Purchasing Power.. Like I said before, make sure You have more than You think You need..

THANK YOU Marty
 
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Hi All;

"" If you do, and you'd consider a group-buy, consider me "in" for some please! THX. ""

Just a reminder, that there would be over a 120 to 140 IC's.. At present I am running at about 150 to 160 IC's, Now some of these may Not be needed and if the options are to use the available parts only, then it could be the higher number.. such as if the 74133 and the 7451 are replaced then three parts become about seven parts..
I have taken out the two 74133's and put in all of the other Parts, but, the sockets are still there for the 74133's..

001.jpg

I just did a parts count, I have 155 so far, but if I eliminate 10 that are for Delays then it becomes 145 count.. And changing back to the 74174's eliminates 6 more IC's..
And I have not even factored in the Memory, nor the I/O..
I think that Dave would have a better idea of an actual number at the present, since he Has implemented both the memory and the I/O..

THANK YOU Marty
 
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Hi All;

I have today so far wired, CIN, Cout, B1, B2, and B4..
I need to fix the equivalent of L8 and L9, reverse the inputs, from my reversing earlier.. This is also done..
And next I need to wire in the Led's for the Accumulator..
The Led's are wired now for the Accumulator..
And I am wiring in the Delay Ic's, I can always take them out at a later time..
Next is Debugging the Accumulator Circuit..
I can input to the Accumulator pin(s) on the 74194 and I get the correct output, I couldn't before as the first six bits were backward on the Led's and I had no clock on the 74194..

003.jpg

THANK YOU Marty
 
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Hi All;

I have at least some of the Accumulator circuit working..
One of the things that is missing in alot of the already wired circuits is the IR Register connection.. So, I think I will go ahead and wire what is needed for that..

THANK YOU Marty
 
Hi All;

Dave, I Understand !! Thanks for Letting us know..

I am going to wire up the Program Counter next.. This will take me awhile to complete..

THANK YOU Marty
 
Marty said:
Hi All;

"" If you do, and you'd consider a group-buy, consider me "in" for some please! THX. ""

Just a reminder, that there would be over a 120 to 140 IC's.. At present I am running at about 150 to 160 IC's, Now some of these may Not be needed and if the options are to use the available parts only, then it could be the higher number.. such as if the 74133 and the 7451 are replaced then three parts become about seven parts..
I have taken out the two 74133's and put in all of the other Parts, but, the sockets are still there for the 74133's..


THANK YOU Marty
Click to expand...

Hi Marty,

have a source of NOS Ti. 74S133 .. at aus$0.88 each for min quantity of 100. there at Rocky electronics in Melbourne Australia, has about 600.

they dont have plain 74133 sadly.

however will try another old stockist in Adelaide, SA tomorrow

regards
David
 
Hi All;

inatrobot, two problems would possibly be, shipping and what to do with 96 more than I could use.. As well as figuring out How to Pay for them..

THANK YOU Marty
 
Looks like Jameco has 74S133 parts in DIP: http://www.jameco.com/1/1/51737-74s133-13-input-nand-gate-dip-16-package-74s-series.html for 99c each.

Also www.acecomponents.com here in San Jose says they have a number of varieties of 74x133 available:

Code: 
74ALS133         554     13 INPUT NAND GATE 2 STATE OUT
74AS133           34     13 INPUT NAND GATE 2 STATE OUT
74F133           406     13 INPUT NAND GATE 2 STATE OUT
74HC133          583     13 INPUT NAND GATE 2 STATE OUT
74S133          1420     13 INPUT NAND GATE 2 STATE OUT

Basically these guys are a giant old dark warehouse chock full of racks and racks of tubes and bins of ICs and components.

You might try giving them a call (they don't have a web order capability) to check pricing and actual availability.

I'll probably be over near them on this Friday so I can stop by and see if I can pickup some parts for you (state your preference).

Let me know if you need me to do this for you, if Jameco does not work out.

Don
 
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Hi Marty,

By end of weekend I will try and get to have a look at the tubes of early IC;s I have put away in my semitrailer.

Maybe I still have a tube or part tube of the standard grade TTL family sn74133, or even just 3 or 4 of.

I assume most if not all of the rest of your ics are not 74S or 74LS or 74F grades but just plain 74xx or 74xxx parts.

Depending on the cct using a S grade part may or may not matter to getting timing and like to occur in the section its used in.
Time will tell if you can only get the 74S part.

If I have a few plain 74xx'x family ones of the 74133 can easily pop them in an post envelope to you.

If you have no joy let me know.
 
Hi All;

Inotarobot, and others, I don't need any of the 74133's, I have what I need to build the unit I have , as well as a few spares..
AK6DN, Thank You for taking the time to find the Parts.. I think once Dave gets back to PDP8 land, He will appreciate that..
Daver2, Said He had trouble finding them.. I suggested that we eliminate them from the build, Especially If they are hard to find.. For future builders of any units, whether by Wire-Wrap or by PCB.. The idea being that all of the IC's are easy obtainable..

THANK YOU Marty
 
Hi All;

I have finished wiring up the Program Counter (L) circuitry.. I have Not wired the Led's for the IR and the PC, that will be next..
Nor have I wired up all of the IR connections, I have wired up many, but, I need to check which have been wired and which have not been wired..
I also, need to find out where to wire the Pc output to, I forgot, and that will be next as well.. Ok, I looked and it's to the MUX..
I have wired up the IR and PC MUX lines, I have started the wiring on the IR/MA lines, I have started the wiring on the MA(L), for the lower MA address lines..
Next I am going to start with Page LD-8 through LD-21 and check what is wired and what is not wired, and correct any non-wired issues..
Here is a picture of the back of the Board, with a few more wires than before..

001.jpg

THANK YOU Marty
 
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Hi All;

LD-8 checks out.. Next is LD-9..
LD-9 and LD-10 check out.. LD-11 is next and that is about 8 pages of Schematics to check..
And I already know that some/much of it is not wired..
LD-11 is mostly done.. Part of LD-11 is the A0-A9 and F0-F10 Delayed, which is NOT in Your circuit, but is in mine..
I have F0-F10 delayed wired, the A0-A9 delayed is next and it will take longer, as none of it is wired, where as some of the F0-F10 was wired..
I have A0-A9 delayed wired.. So, LD-11 is done..
It looks like once I get LD-15 finished with being wired, then all of the other LD's show they have been wired, except for LD-20 which is the 7489's, which I will do next week.. I have started wiring it..
After that then all of the Led's, except for the Accumulator, which has already been wired, and then lastly the switches, Then the Real testing begins..

002.jpg 001.jpg

THANK YOU Marty
 
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Hi All;

I have the 7489's all wired up, and the 74151 MUX's wired up as well.. Yesterday and this morning, I have been away, so things didn't go as fast as I would like.. But, it's getting close..

Next is wiring up of the IR and PC Led's and then the individual Led's..
I have the IR Led's wired in, next is the PC Led's..
The PC Led's is now wired.. Now the individual Led's..
After that it's finding the Mistakes, and Mis-wires and Missing wires..

THANK YOU Marty
 
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