Re: N3101 RAM for Missile Command

It doesn't drive the output resistors, it goes to a latch---the latch
drives the resistors. Like I said, no reason it has to be open collector.

And this game doesn't have a lot of colors, one bit for red, one bit for
green, and one bit for blue. The spare bit does nothing.

John Robertson wrote:

> Open collector is needed when you are driving colour video output
> resistors. You have to have an output gate that floats when it is not
> pulling down the output resistor. You should be able to get the same
> result if you use an isolation diode on each output gate, otherwise
> all the colours will be the same intensity and you won't get that
> lovely 16/32/? colours potential of these old timers...just a nine
> colour palette.
>
> John :-#)#
>
> At 01:28 AM 31/01/2004, Rodger Boots wrote:
>
>> The N3101 is a Signetics number (datasheet here
>> <http://www1.cedar-rapids.net/00000028/IHS/N3101.pdf>) that directly
>> crosses to a 74S289 (datasheet here
>> <http://www1.cedar-rapids.net/00000028/IHS/74s289.pdf>), and for
>> completeness I'm including the Intel 3101 datasheet here.
>> <http://www1.cedar-rapids.net/00000028/IHS/3101.pdf>
>>
>> So far we have chips that are all open collector output and are
>> obsolete. That being said, I see no reason why you need open
>> collector outputs, it's probably just what was available when they
>> designed the game. A 74S189 (Jameco has them here
>> <http://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=1817&cgrfnbr=582&ctgys=502;508;582;>)
>> should work fine.
>>
>> The 3101 is NOT compatible with the 5101 or 2102 or anything else.
>> It is a very fast, very small RAM. 64 bits arranged as 16 x 4.
>>
>>
>> MyPearl wrote:
>>
>>>
>>>Hello group,
>>>
>>>I found that the COLOR RAM (at L7) of my missile command has litterary
>>>cracked open. Weird thing is it, still works, but becomes unstable now
>>>and
>>>then and triggers the Watchdog.
>>>
>>>The partnumber on the chip is 'N3101'
>>>
>>>I cannot find a datasheet for this part, nor a source, or a cross to a
>>>replacement on the web...
>>>
>>>Does anyone know where I could get this RAM, or equivalent?
>>>
>>>Hope someone knows...
>>>
>>>Thanks
>>>
>>>Mendel Pearl
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>>>
>>>
>>>
>>>
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Received on Sat Jan 31 14:46:56 2004