Almost ready to start my NTI build

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Joined: Dec 13 2013
Posts: 18

I have almost collected everything I need and need to make a decision on how to proceed. I have found the 14, 24, and 40 pin TI sockets, but lack the 8 and 16 pin sockets. I do have good quality 8, 14, 16, 24, and 40 pin standard sockets, and wonder if I should just use them and put the TI sockets on eBay, or continue the hunt for the rest of the TI sockets. I've been trying to use as much as I can from my personal parts stash and have all the components, but the CPU I found is a 6502A and my PIA is a 6520. Will they work, or should I keep looking?

I welcome any opinions,

Dick Stachowiak

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Dick Stachowiak
East Syracuse, NY

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speedyG's picture
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Joined: Nov 16 2011
Posts: 2376
Re: Almost ready to start my NTI build

Hello stachowiak,
this depends to your priorities.... :
less time but soon working setup...
or
more time but closer to original comparability.... ?

I´ve been looking for some parts for more than 2 years .... but that has been 2 years ago....

and in that days the 40 pin TI sockets have been the more difficult to find....

I have detected in that days ( 2 years ago ) a huge bunch of 16pin TI sockets and purchased them on behalf
of other members in this board and we performed a kind of collective purchase and mailing.....

maybe this is a good idea even in this days to startup a kind of
"collective" search & hunt and purchase of several members nowadays ?

2 years ago there also has been a Company called SAE that made sockets rather similar looking with even gold contacts.
When the Chips have been inserted there was nearly no difference visible except to experts....
the AES sockets had 2 notches in the socketborder compared to the TI-ones.

Another example: the 6520 PIA is correct and in early boards they used white ceramic cases and in later ones
they have been using ones with plasic cases. I puchased a few in violett ceramic cases with gold pins 2 years ago.

So it´s in a kind of way just a question of luck or fate ( depending to your opinion ).....
Maybe Newton Mike ( he´s also member here - still has some of the 16pin TI sockets in the shelf....)

But one thing of course is for sure...:
while time passes by thiongs get harder and harder while hunting obsolete parts...
and during same time stuff gets more and more expensive....
2 years ago we had some luck and got sockets at fairly normal pricing while a year ago
i´ve seen a guy who demanded 214 U.S. Dollars for an entire TI socket set....

I wish you much luck and some patience while hunting the stuff ....
sincerely speedyG

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the second part includes less friends but a lot more joy on life....

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Joined: Oct 9 2011
Posts: 1044
Re: Almost ready to start my NTI build

A couple of things.

First some things have gotten actually cheaper. 3 years ago a complete set of TI sockets cost almost $400 and that was having to buy 4 sets. So things have come down as people have started looking for these sockets so that you don't need to buy them from a wholesaler with big minimums.

As for the 6520, I don't think that will work. It's a 6820. all the factory units used the unobtainable AMI 6820 in grey plastic with embossed logo. On the Apple-1 this chip is connected to the outside world so easy to blow. When that happened, many people replaced them with ceramic versions from other mfrs or the black AMI 6820 from 1977+ as they were easier to find since the grey plastic AMI 6820 doesn't seem to have been in production for very long.

This AMI grey plastic 6820 is rarer than a ceramic 6502. The only documented from new "factory" ceramic 6820 is the one in the apple advertisement. However I think that board was populated with the best looking chips they could find for the picture.

Cheers,
Corey

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Joined: Jan 1 2015
Posts: 47
Re: Almost ready to start my NTI build

Corey,

When you say the 6520 won't work do you mean functionally, or from a correctness perspective?

Len

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Joined: Oct 9 2011
Posts: 1044
Re: Almost ready to start my NTI build

I don't know anything about the 6520, so I never looked at it as an option. Google has conflicting results. Some pages say yes direct replacement for the 6821, which does work in the A-1. Others say it's not electrically compatible.

So I can't say one way or another.

Cheers,
Corey

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Joined: Oct 4 2014
Posts: 64
Re: Almost ready to start my NTI build

Corey,

The 6520 as well as the 6821 can substituted for the 6820.
I have tried both and they work well on my Apple 1 replicas.

I am surprised Wozniak did not go with the 6520 as it is in the same product family as the 6502.

Online
Joined: Oct 9 2011
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Re: Almost ready to start my NTI build

I guess we can ask Steve, but my guess is that it was chosen because of the 6800 support on the board. It
Also could predate the 6520, the Apple-1 was designed in 1975, I don't know when the 6520 was released.

Cheers,
Corey

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Joined: Dec 13 2013
Posts: 18
Re: Almost ready to start my NTI build

IEEE-802 wrote:

Corey,

The 6520 as well as the 6821 can substituted for the 6820.
I have tried both and they work well on my Apple 1 replicas.

I am surprised Wozniak did not go with the 6520 as it is in the same product family as the 6502.

Thanks for the definitive answer on the 6520. I'm using parts I have in stock and once I get it working I can look for more correct parts. I'm still not sure what to do about the sockets as whatever I pick is not going to be easily replaced later.

Dick Stachowiak

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Dick Stachowiak
East Syracuse, NY