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Expansion board


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Hi folks,


I received my Apple IIc yesterday. While opening the case to change the Rom to 4X, I found an interesting expansion board

I have no clue what it does.

Can anybody tell me what board that is? It seems to be an Z80 board, isn't it?








Edited by wins4
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This board is connected to the CPU socket, right?  I am assuming the 65C02A is your Apple iic CPU.


The NEC D780 googles up to a z80, I don't know if this is a math co-processor expansion or a way to get  Z80 CP/M features into a IIC.  Google failed me on looking for an example of this, but it probably is the only way to expand things in the IIc with its compact form factor.


If you wanted a mockingboard, for example, you have to use your cpu socket as the expansion "slot".  https://www.ebay.com/itm/284305317956



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2 hours ago, magnusfalkirk said:

But if you take a good look at the chip on the upper left of the board it says 'NCR65C02A'. So I don't think it's a Z80. What it is I don't know.


But if you take a good look at the upper right chip, it says NEC D780C. This one is a Z80.

The card plugs into the 65C02 socket so it has to be relocated on the board.


@wins4 You're located in Germany and I see "de" on the card so probably a Z80 clone card made in your country.

It seems pretty close to the Cirtech card (almost the same passives components and number of logic ICs) but with a very different layout. On the Cirtech, the Z80 is below the card :


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The NCR65C02A would be the original 65C02 that shipped with the //c when it it was made. The expansion board is of a piggyback design, pull out the original 65C02 and insert board there. Insert 65C02 into expansion board.


The NEC D780-1 is the 4MHz NEC clone of the original Zilog Z-80. It is pin/register/instruction compatible with the original. Pretty sure t's a low-power part too - you'd have to check the datasheet. This chip is used in several Applied Engineering designs and had a good reputation. And the board looks to be a clone. So many products back then were "no-name" clones. But they all seemed to work as expected.


This board be giv'n you CP/M compatibility! Pretty much any version should work.

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