Re: EEPROM Circuit?

[mjmahon@aol.com (Michael J. Mahon)]

Glenn Jones replied:

>"Michael J. Mahon" <mjmahon@aol.com> wrote in message
>20040409013732.11295.00000077@mb-m15.aol.com">news:20040409013732.11295.00000077@mb-m15.aol.com...
>> Glenn Jones asked:
>>
>> >Speaking of hardware does anyone have any suggestions on how you would
>> >interface a 2k bit eeprom like the Turbo IC 24C02 to the Apple II Bus?
>>
>> I'd be inclined to interface it to the game port rather than the bus.
>>
>> A couple of annunciators for outputs and a pushbutton input and
>> it wouldn't be at all hard to bit-bang the serial interface to the
>> EEPROM without any extra logic.
>>
>> You could just piggyback an 8-pin socket over a 16-pin machined
>> pin socket and plug it into the game port.
>>
>> -michael
>>
>> Check out amazing quality sound for 8-bit Apples on my
>> Home page:  http://members.aol.com/MJMahon/
>
>The reason I am asking is that I am looking for a place to stash
>some config info for for my ethernet card. It would be preferable
>to have that memory on the card.
>
>The other device I was considering was the ibutton.
>http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=2823

You can certainly use a serial device if you wish, but you will
need to provide 2 software "bangable" outputs and an input
on the card to be used by the EEPROM.  My preference,
especially since it will be used only for configuration, is to
use software for the clocking and shifting.

If the ethernet controller has some spare I/O pins, this
would be the most straightforward approach.  Otherwise,
you'll need to use a couple of chips to synthesize them.

In general, byte-wide EEPROMs are much simpler to
interface to a byte-wide bus--in fact the Apple bus has
most of the decoding done for you.

-michael

Check out amazing quality sound for 8-bit Apples on my
Home page:  http://members.aol.com/MJMahon/